SyncValsverifier → artifact → classifier → verdict
SyncVals · Trajectory

Enable-gated streaming fold stage

codex gpt-5.5 ✓ resolved GOOD_SUCCESS ↑ View task
Solved from the instruction alone, tests/ and solution/ were withheld from the agent's workspace and restored only for grading.
Reward = tests/test.sh exit code (0 → resolved); the classification below is post-hoc and cannot change it.
Classification , post-hoc; cannot change the reward
GOOD_SUCCESSLegitimate solve, implements the asked-for behavior; tests verify real functionality.
SubtypeLegitimate Solution
EvidenceAgent implemented fold_stage.sv with correct state management: shift register with proper load/fold phases, round-half-up arithmetic in a helper function, saturating subtraction with explicit sign-extension for overflow handling, enable gating that holds all state on en==0, priming counter that delays out_valid until sample 6, and asynchronous reset. Self-verification testbench passed all checks before submission. Final test output: 'INFO samples=544 dmiss=0 vmiss=0' and 'PASS - 544 samples, no mismatches' with reward=1.0
Root causeAgent correctly implemented a complex streaming datapath with multiple interacting state machines and arithmetic operations, validated the implementation thoroughly with a testbench, and passed all verification checks against the reference specification.
RecommendationN/A - task is fine
Trajectory
Tool-by-tool agent trajectory
27 tool calls · 2 tool types · 44 steps
<permissions instructions> Filesystem sandboxing defines which files can be read or written. `sandbox_mode` is `danger-full-access`: No filesystem sandboxing - all commands are permitted. Network access is enabled. Approval policy is currently never. Do not provide the `sandbox_permissions` for any reason, commands will be rejected. </permissions instructions><apps_instructions> ## Apps (Connectors) Apps (Connectors) can be explicitly triggered in user messages in the format `[$app-name](app://{connector_id})`. Apps can also be implicitly triggered as long as the context suggests usage of available apps. An app is equivalent to a set of MCP tools within the `codex_apps` MCP. An installed app's MCP tools are either provided to you already, or can be lazy-loaded through the `tool_search` tool. If `tool_search` is available, the apps that are searchable by `tools_search` will be listed by it. Do not additionally call list_mcp_resources or list_mcp_resource_templates for apps. </apps_instructions><skills_instructions> ## Skills A skill is a set of instructions provided through a `SKILL.md` source. Below is the list of skills that can be used. Each entry includes a name, description, and source locator. `file` locators are on the host filesystem, `environment resource` locators are owned by an execution environment, `orchestrator resource` locators are opaque non-filesystem resources, and `custom resource` locators use their provider's access mechanism. ### Available skills - imagegen: Generate or edit raster images when the task benefits from AI-created bitmap visuals such as photos, illustrations, textures, sprites, mockups, or transparent-background cutouts. Use when Codex should create a brand-new image, transform an existing image, or derive visual variants from references, and the output should be a bitmap asset rather than repo-native code or vector. Do not use when the task is better handled by editing existing SVG/vector/code-native assets, extending an established icon or logo system, or building the visual directly in HTML/CSS/canvas. (file: /tmp/codex-home/skills/.system/imagegen/SKILL.md) - openai-docs: Use when the user asks how to build with OpenAI products or APIs, asks about Codex itself or choosing Codex surfaces, needs up-to-date official documentation with citations, help choosing the latest model for a use case, or model upgrade and prompt-upgrade guidance; use OpenAI docs MCP tools for non-Codex docs questions, use the Codex manual helper first for broad Codex self-knowledge, and restrict fallback browsing to official OpenAI domains. (file: /tmp/codex-home/skills/.system/openai-docs/SKILL.md) - plugin-creator: Create and scaffold plugin directories for Codex with a required `.codex-plugin/plugin.json`, optional plugin folders/files, valid manifest defaults, and personal-marketplace entries by default. Use when Codex needs to create a new personal plugin, add optional plugin structure, generate or update marketplace entries for plugin ordering and availability metadata, or update an existing local plugin during development with the CLI-driven cachebuster and reinstall flow. (file: /tmp/codex-home/skills/.system/plugin-creator/SKILL.md) - skill-creator: Guide for creating effective skills. This skill should be used when users want to create a new skill (or update an existing skill) that extends Codex's capabilities with specialized knowledge, workflows, or tool integrations. (file: /tmp/codex-home/skills/.system/skill-creator/SKILL.md) - skill-installer: Install Codex skills into $CODEX_HOME/skills from a curated list or a [code-host] repo path. Use when a user asks to list installable skills, install a curated skill, or install a skill from another repo (including private repos). (file: /tmp/codex-home/skills/.system/skill-installer/SKILL.md) ### How to use skills - Discovery: The list above is the skills available in this session (name + description + source locator). `file` entries live on the host filesystem, `environment resource` entries are owned by their execution environment, `orchestrator resource` entries must be accessed through `skills.list` and `skills.read`, and `custom resource` entries use their provider's access mechanism. - Trigger rules: If the user names a skill (with `$SkillName` or plain text) OR the task clearly matches a skill's description shown above, you must use that skill for that turn. Multiple mentions mean use them all. Do not carry skills across turns unless re-mentioned. - Missing/blocked: If a named skill isn't in the list or its source can't be read, say so briefly and continue with the best fallback. - How to use a skill (progressive disclosure): 1) After deciding to use a skill, the main agent must read its `SKILL.md` completely before taking task actions. For a `file` entry, open the listed path. For an `environment resource`, use the filesystem of the owning environment. For an `orchestrator resource`, call `skills.list` with `{"authority":{"kind":"orchestrator"}}`, select the matching package, and pass its `main_resource` to `skills.read`. If a read is truncated or paginated, continue until EOF. 2) When `SKILL.md` references another resource, use the same access mechanism. Resolve relative paths against a filesystem-backed skill directory. For orchestrator skills, pass the exact referenced resource identifier with the same authority and package to `skills.read`; do not treat `skill://` identifiers as filesystem paths. 3) If `SKILL.md` points to extra folders such as `references/`, use its routing instructions to identify the resources required for the task. The main agent must read each required instruction or reference file itself before acting on it. Do not delegate reading, summarizing, or interpreting skill instructions to a subagent. Subagents may still perform task work when the selected skill allows it. 4) For filesystem-backed skills, prefer running or patching provided scripts instead of retyping large code blocks. For orchestrator skills, use `skills.read` and the available tools; do not invent a local path. 5) Reuse provided assets or templates through the same source access mechanism instead of recreating them. - Coordination and sequencing: - If multiple skills apply, choose the minimal set that covers the request and state the order you'll use them. - Announce which skill(s) you're using and why (one short line). If you skip an obvious skill, say why. - Context hygiene: - Progressive disclosure applies to selecting relevant files, not partially reading a selected instruction file. Do not load unrelated references, scripts, or assets. - Avoid deep reference-chasing: prefer opening only files directly linked from `SKILL.md` unless you're blocked. - When variants exist (frameworks, providers, domains), pick only the relevant reference file(s) and note that choice. - Safety and fallback: If a skill can't be applied cleanly (missing files, unclear instructions), state the issue, pick the next-best approach, and continue. </skills_instructions>
<environment_context> <cwd>/work</cwd> <shell>bash</shell> <current_date>2026-06-20</current_date> <timezone>Etc/UTC</timezone> <filesystem><workspace_roots><root>/work</root></workspace_roots><permission_profile type="disabled"><file_system type="unrestricted" /></permission_profile></filesystem> </environment_context>
# Enable-gated streaming fold stage ## Context We need the streaming arithmetic stage `fold_stage` for a back-pressured signal path. Upstream logic hands us one signed 12-bit sample at a time, but only on the cycles it raises an accept strobe; in between, the whole stage has to sit still and hold what it has, because the cycles where `en` is low carry nothing. The one thing that makes this stage fiddly is that a single internal step position drives *three* things at once , whether we are loading or combining, what we feed back into the delay line, and when the output goes live , so all of it has to advance together, one notch per accepted sample, or the stream desynchronises. The package and the wrapper are in place; only `rtl/fold_stage.sv` is a stub. Implement it. ## Interface ``` input clk // single clock input rst_n // asynchronous, active low input en // accept strobe input signed [11:0] din // input sample (two's complement) output signed [11:0] dout // output sample (two's complement) output out_valid // output-live flag ``` ## What "accepted" means A sample is **accepted** on a rising edge of `clk` where `en` is high. On an accepted edge every piece of state moves forward exactly one step. On any rising edge where `en` is low, nothing moves: the delay line, the step position, `dout` and `out_valid` all hold their current values unchanged. `din` is meaningless whenever `en` is low. ## Behaviour The stage holds the four most recently inserted values as a shift register; call the oldest of those four `H`. It walks a repeating cycle of eight accepted samples: the first four are **load** steps, the next four are **combine** steps, then it repeats. - On a **load** step, `dout` is `H`, and `din` is inserted as the newest value (the shift drops what used to be `H`). - On a **combine** step, `dout` is the round-half-up half of `H + din`, and the value inserted into the line is `H - din` **saturated** to the signed 12-bit range , `din` itself is *not* inserted on a combine step. Round-half-up means: add one to the sum, then arithmetic-shift-right by one (`(H + din + 1) >>> 1`). It is not round-to-nearest-even, not round-to-nearest, and not truncation toward zero or toward minus infinity. Saturation means: if `H - din` exceeds `+2047` use `+2047`, if it is below `-2048` use `-2048`, otherwise use it unchanged. `out_valid` is **0 on the first four accepted samples after reset and 1 from the fifth accepted sample onward** (count accepted samples, not clock cycles). It is a level, not a pulse: once high it stays high on every accepted sample, and like every other output it holds its value across `en`-low cycles. ## Conventions `dout` and `out_valid` are **registered**: they take their new value on the accepted rising edge and are observable from just after that edge until the next accepted edge. The result of an accepted sample lands on `dout` on that sample's **own** accepted edge , a single registered stage, no extra pipeline delay , and a combine output uses the `din` present on that same edge. `rst_n` is **asynchronous** and **active low**: while it is low the four-deep line is cleared to zero, the step position returns to the first load step, and `dout` and `out_valid` are forced to 0, immediately on the falling edge of `rst_n` rather than waiting for a clock, and reset wins over `en`. The step position holds through `en`-low gaps, so a gap does not change which samples pair up. For an accepted output on edge `E`, with two idle cycles after it: ``` edge E E+1 E+2 E+3 en 1 0 0 1 dout A A A B out_valid 1 1 1 1 ``` ## Submission Write your implementation into `rtl/fold_stage.sv`, keeping the module name, ports and parameters exactly as given. It must elaborate under Icarus Verilog 11 (`iverilog -g2012`); note that on that tool a bit- or part-select of an *expression* (a sum, a shift, a function result) is a syntax error, so do any such bit work inside a `function automatic` on a named value. The grader compiles your stage with a held-back checker and compares `dout` and `out_valid` cycle by cycle against a reference over directed and random stimulus.
I’ll inspect the existing wrapper/package and the stub first, then patch only `rtl/fold_stage.sv` and run the available compile/tests if present.
shell
pwd && rg --files
output
Chunk ID: 692ba3
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 22
Output:
/work
fold_core/rtl/fold_top.sv
fold_core/rtl/fold_stage.sv
fold_core/rtl/fold_pkg.sv
shell
sed -n '1,220p' rtl/fold_stage.sv
output
Chunk ID: 7af353
Wall time: 0.0000 seconds
Process exited with code 2
Original token count: 16
Output:
sed: can't read rtl/fold_stage.sv: No such file or directory
shell
find . -maxdepth 3 -type f \( -name '*.sv' -o -name '*.v' -o -name 'Makefile' -o -name '*.mk' \) -print
output
Chunk ID: 31e136
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 22
Output:
./fold_core/rtl/fold_pkg.sv
./fold_core/rtl/fold_stage.sv
./fold_core/rtl/fold_top.sv
The project root is `/work/fold_core`, so I’m switching there. I found only the three RTL files, which keeps the change narrowly scoped.
shell
sed -n '1,240p' rtl/fold_stage.sv
output
Chunk ID: 0ab3d3
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 706
Output:
//==============================================================================
// fold_stage.sv
//
// Enable-gated streaming fold stage.
//
// ---------------------------------------------------------------------------
//  >>> IMPLEMENTATION REQUIRED <<<
//
//  The module ports, parameters and the state registers are provided. The
//  datapath, the phase/priming control and the outputs are left as a TODO and
//  currently drive constant zeros, so the stage produces no useful stream and
//  the verifier FAILS.
//
//  Implement the behaviour described in instruction.md. Do NOT change the
//  module name, the port list, or the parameter list.
//
//  iverilog 11 note: a bit/part-select of an EXPRESSION (a sum, a shift, a
//  function-call result) is a syntax error under `iverilog -g2012`. Index only
//  named signals, and do any bit work that needs an intermediate value inside a
//  `function automatic` using named locals.
// ---------------------------------------------------------------------------
//==============================================================================
`timescale 1ns/1ps

module fold_stage #(
    parameter DW    = 12,
    parameter DEPTH = 4,
    parameter NPH   = 8
) (
    input  logic                     clk,
    input  logic                     rst_n,
    input  logic                     en,
    input  logic signed [DW-1:0]     din,
    output logic signed [DW-1:0]     dout,
    output logic                     out_valid
);

  // ---------------------------------------------------------------------------
  // State registers (provided). The head of the feedback line is line[DEPTH-1].
  // ---------------------------------------------------------------------------
  logic signed [DW-1:0] line [0:DEPTH-1];
  logic         [2:0]   phase;
  logic         [2:0]   prime;
  integer               k;

  // ===========================================================================
  // TODO: IMPLEMENT THE STAGE.
  //   * advance every register exactly one step on a rising clk edge with en==1,
  //     and hold all of it when en==0;
  //   * asynchronous active-low reset clears state and outputs;
  //   * drive dout / out_valid per the contract in instruction.md.
  //
  // The placeholder below keeps the module compilable but INCORRECT.
  // ===========================================================================
  always_ff @(posedge clk or negedge rst_n) begin
    if (!rst_n) begin
      for (k = 0; k < DEPTH; k = k + 1) line[k] <= '0;
      phase <= 3'd0;
      prime <= 3'd0;
    end else begin
      // TODO: replace with the real datapath + control.
      phase <= phase;
      prime <= prime;
    end
  end

  // TODO: replace these placeholder outputs with the real ones.
  assign dout      = '0;
  assign out_valid = 1'b0;

endmodule : fold_stage
shell
sed -n '1,220p' rtl/fold_pkg.sv
output
Chunk ID: 32efe4
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 227
Output:
//==============================================================================
// fold_pkg.sv
//
// Shared geometry for the enable-gated streaming fold stage. The block carries a
// DEPTH-deep signed feedback line, an eight-step phase counter, and a small
// priming counter. Parameters are declared without an explicit data type for
// broad simulator compatibility (Icarus Verilog 11); they default to integer
// constants, which is sufficient here.
//
// DO NOT change this file.
//==============================================================================
`ifndef FOLD_PKG_SV
`define FOLD_PKG_SV

package fold_pkg;

  localparam DW    = 12;   // sample word width (signed two's complement)
  localparam DEPTH = 4;    // feedback line depth (= load/combine window length)
  localparam NPH   = 8;    // phase counter span: 0..3 load window, 4..7 combine

endpackage : fold_pkg

`endif // FOLD_PKG_SV
shell
sed -n '1,240p' rtl/fold_top.sv
output
Chunk ID: 5c0157
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 292
Output:
//==============================================================================
// fold_top.sv
//
// Thin integration wrapper. The verification environment drives this wrapper so
// that the instantiation wiring is exercised alongside the stage itself. It
// instantiates fold_stage with the project-default geometry from fold_pkg.
//
// DO NOT change this file.
//==============================================================================
`timescale 1ns/1ps
`include "fold_pkg.sv"

module fold_top (
    input  logic                             clk,
    input  logic                             rst_n,
    input  logic                             en,
    input  logic signed [fold_pkg::DW-1:0]   din,
    output logic signed [fold_pkg::DW-1:0]   dout,
    output logic                             out_valid
);

  // Bare instantiation: the stage carries its own default geometry, so a
  // submission needs no parameter override to elaborate correctly.
  fold_stage u_fold_stage (
      .clk       (clk),
      .rst_n     (rst_n),
      .en        (en),
      .din       (din),
      .dout      (dout),
      .out_valid (out_valid)
  );

endmodule : fold_top
shell
git status --short
output
Chunk ID: fe739b
Wall time: 0.0000 seconds
Process exited with code 127
Original token count: 11
Output:
/bin/bash: line 1: git: command not found
I’m going to make `dout` and `out_valid` true registers in the same enable-gated sequential block as the delay line. The current `phase` value will drive load vs combine for that accepted edge, then advance only when `en` is high.
apply_patch
*** Begin Patch
*** Update File: /work/fold_core/rtl/fold_stage.sv
@@
   logic signed [DW-1:0] line [0:DEPTH-1];
   logic         [2:0]   phase;
   logic         [2:0]   prime;
   integer               k;
 
-  // ===========================================================================
-  // TODO: IMPLEMENT THE STAGE.
-  //   * advance every register exactly one step on a rising clk edge with en==1,
-  //     and hold all of it when en==0;
-  //   * asynchronous active-low reset clears state and outputs;
-  //   * drive dout / out_valid per the contract in instruction.md.
-  //
-  // The placeholder below keeps the module compilable but INCORRECT.
-  // ===========================================================================
+  function automatic logic signed [DW-1:0] round_half_up;
+    input logic signed [DW-1:0] a;
+    input logic signed [DW-1:0] b;
+    logic signed [DW:0] sum_plus_one;
+    logic signed [DW:0] half;
+    begin
+      sum_plus_one = a + b + 1;
+      half         = sum_plus_one >>> 1;
+      round_half_up = half[DW-1:0];
+    end
+  endfunction
+
+  function automatic logic signed [DW-1:0] sat_sub;
+    input logic signed [DW-1:0] a;
+    input logic signed [DW-1:0] b;
+    logic signed [DW:0] diff;
+    logic signed [DW:0] max_val;
+    logic signed [DW:0] min_val;
+    begin
+      diff    = a - b;
+      max_val = $signed({1'b0, {(DW-1){1'b1}}});
+      min_val = $signed({1'b1, {(DW-1){1'b0}}});
+
+      if (diff > max_val) begin
+        sat_sub = max_val[DW-1:0];
+      end else if (diff < min_val) begin
+        sat_sub = min_val[DW-1:0];
+      end else begin
+        sat_sub = diff[DW-1:0];
+      end
+    end
+  endfunction
+
   always_ff @(posedge clk or negedge rst_n) begin
     if (!rst_n) begin
       for (k = 0; k < DEPTH; k = k + 1) line[k] <= '0;
-      phase <= 3'd0;
-      prime <= 3'd0;
+      phase     <= 3'd0;
+      prime     <= 3'd0;
+      dout      <= '0;
+      out_valid <= 1'b0;
     end else begin
-      // TODO: replace with the real datapath + control.
-      phase <= phase;
-      prime <= prime;
+      if (en) begin
+        if (phase < DEPTH[2:0]) begin
+          dout    <= line[DEPTH-1];
+          line[0] <= din;
+        end else begin
+          dout    <= round_half_up(line[DEPTH-1], din);
+          line[0] <= sat_sub(line[DEPTH-1], din);
+        end
+
+        for (k = 1; k < DEPTH; k = k + 1) line[k] <= line[k-1];
+
+        if (phase == (NPH-1)) begin
+          phase <= 3'd0;
+        end else begin
+          phase <= phase + 3'd1;
+        end
+
+        if (prime < DEPTH[2:0]) begin
+          prime <= prime + 3'd1;
+        end
+
+        out_valid <= (prime >= DEPTH[2:0]);
+      end
     end
   end
-
-  // TODO: replace these placeholder outputs with the real ones.
-  assign dout      = '0;
-  assign out_valid = 1'b0;
 
 endmodule : fold_stage
*** End Patch


Exit code: 0
Wall time: 0 seconds
Output:
Success. Updated the following files:
M /work/fold_core/rtl/fold_stage.sv
I noticed one arithmetic detail while reviewing the patch: signed add/subtract need an explicit extra bit before the operation, otherwise Verilog can evaluate in the original 12-bit width and overflow before assignment. I’m tightening that before compiling.
apply_patch
*** Begin Patch
*** Update File: /work/fold_core/rtl/fold_stage.sv
@@
     input logic signed [DW-1:0] a;
     input logic signed [DW-1:0] b;
+    logic signed [DW:0] a_ext;
+    logic signed [DW:0] b_ext;
     logic signed [DW:0] sum_plus_one;
     logic signed [DW:0] half;
     begin
-      sum_plus_one = a + b + 1;
+      a_ext        = {a[DW-1], a};
+      b_ext        = {b[DW-1], b};
+      sum_plus_one = a_ext + b_ext + 1;
       half         = sum_plus_one >>> 1;
       round_half_up = half[DW-1:0];
     end
   endfunction
 
@@
     input logic signed [DW-1:0] a;
     input logic signed [DW-1:0] b;
+    logic signed [DW:0] a_ext;
+    logic signed [DW:0] b_ext;
     logic signed [DW:0] diff;
     logic signed [DW:0] max_val;
     logic signed [DW:0] min_val;
     begin
-      diff    = a - b;
+      a_ext   = {a[DW-1], a};
+      b_ext   = {b[DW-1], b};
+      diff    = a_ext - b_ext;
*** End Patch


Exit code: 0
Wall time: 0 seconds
Output:
Success. Updated the following files:
M /work/fold_core/rtl/fold_stage.sv
The datapath is now explicit about widened arithmetic and saturation bounds. I’m compiling with Icarus next, then I’ll add a small local self-check if there isn’t an existing testbench.
shell
iverilog -g2012 -Wall -I rtl -o /tmp/fold_compile.vvp rtl/fold_pkg.sv rtl/fold_stage.sv rtl/fold_top.sv
output
Chunk ID: d228fc
Wall time: 0.0003 seconds
Process exited with code 4
Original token count: 48
Output:
rtl/fold_stage.sv:47: syntax error
rtl/fold_stage.sv:46: error: Syntax error defining function.
rtl/fold_stage.sv:63: syntax error
rtl/fold_stage.sv:62: error: Syntax error defining function.
shell
sed -n '1,220p' rtl/fold_stage.sv
output
Chunk ID: 020317
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 980
Output:
//==============================================================================
// fold_stage.sv
//
// Enable-gated streaming fold stage.
//
// ---------------------------------------------------------------------------
//  >>> IMPLEMENTATION REQUIRED <<<
//
//  The module ports, parameters and the state registers are provided. The
//  datapath, the phase/priming control and the outputs are left as a TODO and
//  currently drive constant zeros, so the stage produces no useful stream and
//  the verifier FAILS.
//
//  Implement the behaviour described in instruction.md. Do NOT change the
//  module name, the port list, or the parameter list.
//
//  iverilog 11 note: a bit/part-select of an EXPRESSION (a sum, a shift, a
//  function-call result) is a syntax error under `iverilog -g2012`. Index only
//  named signals, and do any bit work that needs an intermediate value inside a
//  `function automatic` using named locals.
// ---------------------------------------------------------------------------
//==============================================================================
`timescale 1ns/1ps

module fold_stage #(
    parameter DW    = 12,
    parameter DEPTH = 4,
    parameter NPH   = 8
) (
    input  logic                     clk,
    input  logic                     rst_n,
    input  logic                     en,
    input  logic signed [DW-1:0]     din,
    output logic signed [DW-1:0]     dout,
    output logic                     out_valid
);

  // ---------------------------------------------------------------------------
  // State registers (provided). The head of the feedback line is line[DEPTH-1].
  // ---------------------------------------------------------------------------
  logic signed [DW-1:0] line [0:DEPTH-1];
  logic         [2:0]   phase;
  logic         [2:0]   prime;
  integer               k;

  function automatic logic signed [DW-1:0] round_half_up;
    input logic signed [DW-1:0] a;
    input logic signed [DW-1:0] b;
    logic signed [DW:0] a_ext;
    logic signed [DW:0] b_ext;
    logic signed [DW:0] sum_plus_one;
    logic signed [DW:0] half;
    begin
      a_ext        = {a[DW-1], a};
      b_ext        = {b[DW-1], b};
      sum_plus_one = a_ext + b_ext + 1;
      half         = sum_plus_one >>> 1;
      round_half_up = half[DW-1:0];
    end
  endfunction

  function automatic logic signed [DW-1:0] sat_sub;
    input logic signed [DW-1:0] a;
    input logic signed [DW-1:0] b;
    logic signed [DW:0] a_ext;
    logic signed [DW:0] b_ext;
    logic signed [DW:0] diff;
    logic signed [DW:0] max_val;
    logic signed [DW:0] min_val;
    begin
      a_ext   = {a[DW-1], a};
      b_ext   = {b[DW-1], b};
      diff    = a_ext - b_ext;
      max_val = $signed({1'b0, {(DW-1){1'b1}}});
      min_val = $signed({1'b1, {(DW-1){1'b0}}});

      if (diff > max_val) begin
        sat_sub = max_val[DW-1:0];
      end else if (diff < min_val) begin
        sat_sub = min_val[DW-1:0];
      end else begin
        sat_sub = diff[DW-1:0];
      end
    end
  endfunction

  always_ff @(posedge clk or negedge rst_n) begin
    if (!rst_n) begin
      for (k = 0; k < DEPTH; k = k + 1) line[k] <= '0;
      phase     <= 3'd0;
      prime     <= 3'd0;
      dout      <= '0;
      out_valid <= 1'b0;
    end else begin
      if (en) begin
        if (phase < DEPTH[2:0]) begin
          dout    <= line[DEPTH-1];
          line[0] <= din;
        end else begin
          dout    <= round_half_up(line[DEPTH-1], din);
          line[0] <= sat_sub(line[DEPTH-1], din);
        end

        for (k = 1; k < DEPTH; k = k + 1) line[k] <= line[k-1];

        if (phase == (NPH-1)) begin
          phase <= 3'd0;
        end else begin
          phase <= phase + 3'd1;
        end

        if (prime < DEPTH[2:0]) begin
          prime <= prime + 3'd1;
        end

        out_valid <= (prime >= DEPTH[2:0]);
      end
    end
  end

endmodule : fold_stage
shell
nl -ba rtl/fold_stage.sv | sed -n '36,70p'
output
Chunk ID: e29189
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 348
Output:
    36	);
    37	
    38	  // ---------------------------------------------------------------------------
    39	  // State registers (provided). The head of the feedback line is line[DEPTH-1].
    40	  // ---------------------------------------------------------------------------
    41	  logic signed [DW-1:0] line [0:DEPTH-1];
    42	  logic         [2:0]   phase;
    43	  logic         [2:0]   prime;
    44	  integer               k;
    45	
    46	  function automatic logic signed [DW-1:0] round_half_up;
    47	    input logic signed [DW-1:0] a;
    48	    input logic signed [DW-1:0] b;
    49	    logic signed [DW:0] a_ext;
    50	    logic signed [DW:0] b_ext;
    51	    logic signed [DW:0] sum_plus_one;
    52	    logic signed [DW:0] half;
    53	    begin
    54	      a_ext        = {a[DW-1], a};
    55	      b_ext        = {b[DW-1], b};
    56	      sum_plus_one = a_ext + b_ext + 1;
    57	      half         = sum_plus_one >>> 1;
    58	      round_half_up = half[DW-1:0];
    59	    end
    60	  endfunction
    61	
    62	  function automatic logic signed [DW-1:0] sat_sub;
    63	    input logic signed [DW-1:0] a;
    64	    input logic signed [DW-1:0] b;
    65	    logic signed [DW:0] a_ext;
    66	    logic signed [DW:0] b_ext;
    67	    logic signed [DW:0] diff;
    68	    logic signed [DW:0] max_val;
    69	    logic signed [DW:0] min_val;
    70	    begin
apply_patch
*** Begin Patch
*** Update File: /work/fold_core/rtl/fold_stage.sv
@@
-  function automatic logic signed [DW-1:0] round_half_up;
+  function automatic signed [DW-1:0] round_half_up;
@@
-  function automatic logic signed [DW-1:0] sat_sub;
+  function automatic signed [DW-1:0] sat_sub;
*** End Patch


Exit code: 0
Wall time: 0 seconds
Output:
Success. Updated the following files:
M /work/fold_core/rtl/fold_stage.sv
Icarus 11 rejected the newer function return syntax, so I adjusted the functions to the older SystemVerilog form it accepts. The behavior is unchanged.
shell
iverilog -g2012 -Wall -I rtl -o /tmp/fold_compile.vvp rtl/fold_pkg.sv rtl/fold_stage.sv rtl/fold_top.sv
output
Chunk ID: 23e54a
Wall time: 0.0000 seconds
Process exited with code 4
Original token count: 48
Output:
rtl/fold_stage.sv:47: syntax error
rtl/fold_stage.sv:46: error: Syntax error defining function.
rtl/fold_stage.sv:63: syntax error
rtl/fold_stage.sv:62: error: Syntax error defining function.
apply_patch
*** Begin Patch
*** Update File: /work/fold_core/rtl/fold_stage.sv
@@
-    input logic signed [DW-1:0] a;
-    input logic signed [DW-1:0] b;
+    input signed [DW-1:0] a;
+    input signed [DW-1:0] b;
@@
-    input logic signed [DW-1:0] a;
-    input logic signed [DW-1:0] b;
+    input signed [DW-1:0] a;
+    input signed [DW-1:0] b;
*** End Patch


Exit code: 0
Wall time: 0 seconds
Output:
Success. Updated the following files:
M /work/fold_core/rtl/fold_stage.sv
shell
iverilog -g2012 -Wall -I rtl -o /tmp/fold_compile.vvp rtl/fold_pkg.sv rtl/fold_stage.sv rtl/fold_top.sv
output
Chunk ID: 1ecaa1
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 59
Output:
warning: Some design elements have no explicit time unit and/or
       : time precision. This may cause confusing timing results.
       : Affected design elements are:
       :   -- package fold_pkg declared here: rtl/fold_pkg.sv:15
The RTL now elaborates. I’m adding a temporary self-checking testbench to exercise load/combine sequencing, saturation, rounding, and enable gaps against a simple reference model, then I’ll remove the testbench afterward.
apply_patch
*** Begin Patch
*** Add File: /work/fold_core/tb_fold_stage_tmp.sv
+`timescale 1ns/1ps
+
+module tb_fold_stage_tmp;
+  localparam DW = 12;
+  localparam DEPTH = 4;
+  localparam NPH = 8;
+
+  logic clk;
+  logic rst_n;
+  logic en;
+  logic signed [DW-1:0] din;
+  logic signed [DW-1:0] dout;
+  logic out_valid;
+
+  logic signed [DW-1:0] ref_line [0:DEPTH-1];
+  logic signed [DW-1:0] next_line [0:DEPTH-1];
+  logic signed [DW-1:0] ref_dout;
+  logic signed [DW-1:0] next_dout;
+  logic ref_valid;
+  logic next_valid;
+  integer ref_phase;
+  integer ref_prime;
+  integer next_phase;
+  integer next_prime;
+  integer i;
+  integer n;
+  integer errors;
+
+  fold_stage dut (
+      .clk       (clk),
+      .rst_n     (rst_n),
+      .en        (en),
+      .din       (din),
+      .dout      (dout),
+      .out_valid (out_valid)
+  );
+
+  initial begin
+    clk = 1'b0;
+    forever #5 clk = ~clk;
+  end
+
+  function automatic signed [DW-1:0] ref_round;
+    input signed [DW-1:0] a;
+    input signed [DW-1:0] b;
+    integer sum;
+    begin
+      sum = a + b + 1;
+      ref_round = sum >>> 1;
+    end
+  endfunction
+
+  function automatic signed [DW-1:0] ref_sat_sub;
+    input signed [DW-1:0] a;
+    input signed [DW-1:0] b;
+    integer diff;
+    begin
+      diff = a - b;
+      if (diff > 2047) begin
+        ref_sat_sub = 2047;
+      end else if (diff < -2048) begin
+        ref_sat_sub = -2048;
+      end else begin
+        ref_sat_sub = diff;
+      end
+    end
+  endfunction
+
+  task automatic reset_ref;
+    begin
+      for (i = 0; i < DEPTH; i = i + 1) ref_line[i] = '0;
+      ref_phase = 0;
+      ref_prime = 0;
+      ref_dout = '0;
+      ref_valid = 1'b0;
+    end
+  endtask
+
+  task automatic drive_sample;
+    input sample_en;
+    input signed [DW-1:0] sample;
+    begin
+      en = sample_en;
+      din = sample;
+
+      for (i = 0; i < DEPTH; i = i + 1) next_line[i] = ref_line[i];
+      next_phase = ref_phase;
+      next_prime = ref_prime;
+      next_dout = ref_dout;
+      next_valid = ref_valid;
+
+      if (sample_en) begin
+        if (ref_phase < DEPTH) begin
+          next_dout = ref_line[DEPTH-1];
+          next_line[0] = sample;
+        end else begin
+          next_dout = ref_round(ref_line[DEPTH-1], sample);
+          next_line[0] = ref_sat_sub(ref_line[DEPTH-1], sample);
+        end
+
+        for (i = 1; i < DEPTH; i = i + 1) next_line[i] = ref_line[i-1];
+        next_phase = (ref_phase == (NPH-1)) ? 0 : ref_phase + 1;
+        next_prime = (ref_prime < DEPTH) ? ref_prime + 1 : ref_prime;
+        next_valid = (ref_prime >= DEPTH);
+      end
+
+      @(posedge clk);
+      #1;
+      if (dout !== next_dout || out_valid !== next_valid) begin
+        $display("mismatch en=%0d din=%0d phase=%0d prime=%0d got dout=%0d valid=%0d exp dout=%0d valid=%0d",
+                 sample_en, sample, ref_phase, ref_prime, dout, out_valid, next_dout, next_valid);
+        errors = errors + 1;
+      end
+
+      for (i = 0; i < DEPTH; i = i + 1) ref_line[i] = next_line[i];
+      ref_phase = next_phase;
+      ref_prime = next_prime;
+      ref_dout = next_dout;
+      ref_valid = next_valid;
+    end
+  endtask
+
+  initial begin
+    errors = 0;
+    reset_ref();
+    rst_n = 1'b0;
+    en = 1'b0;
+    din = '0;
+
+    #2;
+    if (dout !== '0 || out_valid !== 1'b0) begin
+      $display("reset mismatch");
+      errors = errors + 1;
+    end
+
+    @(negedge clk);
+    rst_n = 1'b1;
+
+    drive_sample(1'b1, 12'sd10);
+    drive_sample(1'b0, -12'sd77);
+    drive_sample(1'b0, 12'sd123);
+    drive_sample(1'b1, -12'sd20);
+    drive_sample(1'b1, 12'sd30);
+    drive_sample(1'b1, -12'sd40);
+    drive_sample(1'b1, 12'sd7);
+    drive_sample(1'b1, -12'sd2048);
+    drive_sample(1'b1, 12'sd2047);
+    drive_sample(1'b0, 12'sd0);
+    drive_sample(1'b1, -12'sd1);
+
+    for (n = 0; n < 300; n = n + 1) begin
+      drive_sample($urandom_range(0, 1), $signed($urandom_range(0, 4095)));
+    end
+
+    #3;
+    rst_n = 1'b0;
+    reset_ref();
+    #1;
+    if (dout !== '0 || out_valid !== 1'b0) begin
+      $display("async reset mismatch");
+      errors = errors + 1;
+    end
+    @(negedge clk);
+    rst_n = 1'b1;
+
+    for (n = 0; n < 40; n = n + 1) begin
+      drive_sample(1'b1, n - 20);
+    end
+
+    if (errors == 0) begin
+      $display("PASS");
+    end else begin
+      $display("FAIL errors=%0d", errors);
+      $fatal(1);
+    end
+    $finish;
+  end
+endmodule
*** End Patch


Exit code: 0
Wall time: 0 seconds
Output:
Success. Updated the following files:
A /work/fold_core/tb_fold_stage_tmp.sv
The temporary checker is in place. It includes idle cycles where `din` changes, so it should catch accidental advancement during `en == 0` as well as arithmetic edge cases.
shell
iverilog -g2012 -Wall -I rtl -o /tmp/fold_tb.vvp rtl/fold_stage.sv tb_fold_stage_tmp.sv && vvp /tmp/fold_tb.vvp
output
Chunk ID: dc5d96
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 2
Output:
PASS
The self-check passed. I’m removing the temporary testbench now so the repository is left with only the requested RTL change.
apply_patch
*** Begin Patch
*** Delete File: /work/fold_core/tb_fold_stage_tmp.sv
*** End Patch


Exit code: 0
Wall time: 0 seconds
Output:
Success. Updated the following files:
D /work/fold_core/tb_fold_stage_tmp.sv
The scratch testbench is gone. I’m doing one final clean compile of the remaining RTL and a quick file review for line references.
shell
iverilog -g2012 -Wall -I rtl -o /tmp/fold_compile.vvp rtl/fold_pkg.sv rtl/fold_stage.sv rtl/fold_top.sv
output
Chunk ID: c5d293
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 59
Output:
warning: Some design elements have no explicit time unit and/or
       : time precision. This may cause confusing timing results.
       : Affected design elements are:
       :   -- package fold_pkg declared here: rtl/fold_pkg.sv:15
shell
nl -ba rtl/fold_stage.sv | sed -n '1,180p'
output
Chunk ID: 18554f
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 1182
Output:
     1	//==============================================================================
     2	// fold_stage.sv
     3	//
     4	// Enable-gated streaming fold stage.
     5	//
     6	// ---------------------------------------------------------------------------
     7	//  >>> IMPLEMENTATION REQUIRED <<<
     8	//
     9	//  The module ports, parameters and the state registers are provided. The
    10	//  datapath, the phase/priming control and the outputs are left as a TODO and
    11	//  currently drive constant zeros, so the stage produces no useful stream and
    12	//  the verifier FAILS.
    13	//
    14	//  Implement the behaviour described in instruction.md. Do NOT change the
    15	//  module name, the port list, or the parameter list.
    16	//
    17	//  iverilog 11 note: a bit/part-select of an EXPRESSION (a sum, a shift, a
    18	//  function-call result) is a syntax error under `iverilog -g2012`. Index only
    19	//  named signals, and do any bit work that needs an intermediate value inside a
    20	//  `function automatic` using named locals.
    21	// ---------------------------------------------------------------------------
    22	//==============================================================================
    23	`timescale 1ns/1ps
    24	
    25	module fold_stage #(
    26	    parameter DW    = 12,
    27	    parameter DEPTH = 4,
    28	    parameter NPH   = 8
    29	) (
    30	    input  logic                     clk,
    31	    input  logic                     rst_n,
    32	    input  logic                     en,
    33	    input  logic signed [DW-1:0]     din,
    34	    output logic signed [DW-1:0]     dout,
    35	    output logic                     out_valid
    36	);
    37	
    38	  // ---------------------------------------------------------------------------
    39	  // State registers (provided). The head of the feedback line is line[DEPTH-1].
    40	  // ---------------------------------------------------------------------------
    41	  logic signed [DW-1:0] line [0:DEPTH-1];
    42	  logic         [2:0]   phase;
    43	  logic         [2:0]   prime;
    44	  integer               k;
    45	
    46	  function automatic signed [DW-1:0] round_half_up;
    47	    input signed [DW-1:0] a;
    48	    input signed [DW-1:0] b;
    49	    logic signed [DW:0] a_ext;
    50	    logic signed [DW:0] b_ext;
    51	    logic signed [DW:0] sum_plus_one;
    52	    logic signed [DW:0] half;
    53	    begin
    54	      a_ext        = {a[DW-1], a};
    55	      b_ext        = {b[DW-1], b};
    56	      sum_plus_one = a_ext + b_ext + 1;
    57	      half         = sum_plus_one >>> 1;
    58	      round_half_up = half[DW-1:0];
    59	    end
    60	  endfunction
    61	
    62	  function automatic signed [DW-1:0] sat_sub;
    63	    input signed [DW-1:0] a;
    64	    input signed [DW-1:0] b;
    65	    logic signed [DW:0] a_ext;
    66	    logic signed [DW:0] b_ext;
    67	    logic signed [DW:0] diff;
    68	    logic signed [DW:0] max_val;
    69	    logic signed [DW:0] min_val;
    70	    begin
    71	      a_ext   = {a[DW-1], a};
    72	      b_ext   = {b[DW-1], b};
    73	      diff    = a_ext - b_ext;
    74	      max_val = $signed({1'b0, {(DW-1){1'b1}}});
    75	      min_val = $signed({1'b1, {(DW-1){1'b0}}});
    76	
    77	      if (diff > max_val) begin
    78	        sat_sub = max_val[DW-1:0];
    79	      end else if (diff < min_val) begin
    80	        sat_sub = min_val[DW-1:0];
    81	      end else begin
    82	        sat_sub = diff[DW-1:0];
    83	      end
    84	    end
    85	  endfunction
    86	
    87	  always_ff @(posedge clk or negedge rst_n) begin
    88	    if (!rst_n) begin
    89	      for (k = 0; k < DEPTH; k = k + 1) line[k] <= '0;
    90	      phase     <= 3'd0;
    91	      prime     <= 3'd0;
    92	      dout      <= '0;
    93	      out_valid <= 1'b0;
    94	    end else begin
    95	      if (en) begin
    96	        if (phase < DEPTH[2:0]) begin
    97	          dout    <= line[DEPTH-1];
    98	          line[0] <= din;
    99	        end else begin
   100	          dout    <= round_half_up(line[DEPTH-1], din);
   101	          line[0] <= sat_sub(line[DEPTH-1], din);
   102	        end
   103	
   104	        for (k = 1; k < DEPTH; k = k + 1) line[k] <= line[k-1];
   105	
   106	        if (phase == (NPH-1)) begin
   107	          phase <= 3'd0;
   108	        end else begin
   109	          phase <= phase + 3'd1;
   110	        end
   111	
   112	        if (prime < DEPTH[2:0]) begin
   113	          prime <= prime + 3'd1;
   114	        end
   115	
   116	        out_valid <= (prime >= DEPTH[2:0]);
   117	      end
   118	    end
   119	  end
   120	
   121	endmodule : fold_stage
shell
find . -maxdepth 2 -type f -print | sort
output
Chunk ID: 0c3b10
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 14
Output:
./rtl/fold_pkg.sv
./rtl/fold_stage.sv
./rtl/fold_top.sv
The final compile is clean apart from the existing package time-unit warning. I’m making one small cleanup to avoid comparing the phase counter against part-selected parameters directly.
apply_patch
*** Begin Patch
*** Update File: /work/fold_core/rtl/fold_stage.sv
@@
   logic signed [DW-1:0] line [0:DEPTH-1];
   logic         [2:0]   phase;
   logic         [2:0]   prime;
   integer               k;
+  localparam [2:0]      LOAD_STEPS = DEPTH;
+  localparam [2:0]      LAST_PHASE = NPH - 1;
@@
-        if (phase < DEPTH[2:0]) begin
+        if (phase < LOAD_STEPS) begin
@@
-        if (phase == (NPH-1)) begin
+        if (phase == LAST_PHASE) begin
@@
-        if (prime < DEPTH[2:0]) begin
+        if (prime < LOAD_STEPS) begin
           prime <= prime + 3'd1;
         end
 
-        out_valid <= (prime >= DEPTH[2:0]);
+        out_valid <= (prime >= LOAD_STEPS);
*** End Patch


Exit code: 0
Wall time: 0 seconds
Output:
Success. Updated the following files:
M /work/fold_core/rtl/fold_stage.sv
shell
iverilog -g2012 -Wall -I rtl -o /tmp/fold_compile.vvp rtl/fold_pkg.sv rtl/fold_stage.sv rtl/fold_top.sv
output
Chunk ID: 0b5f4f
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 59
Output:
warning: Some design elements have no explicit time unit and/or
       : time precision. This may cause confusing timing results.
       : Affected design elements are:
       :   -- package fold_pkg declared here: rtl/fold_pkg.sv:15
shell
nl -ba rtl/fold_stage.sv | sed -n '41,124p'
output
Chunk ID: 868772
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 709
Output:
    41	  logic signed [DW-1:0] line [0:DEPTH-1];
    42	  logic         [2:0]   phase;
    43	  logic         [2:0]   prime;
    44	  integer               k;
    45	  localparam [2:0]      LOAD_STEPS = DEPTH;
    46	  localparam [2:0]      LAST_PHASE = NPH - 1;
    47	
    48	  function automatic signed [DW-1:0] round_half_up;
    49	    input signed [DW-1:0] a;
    50	    input signed [DW-1:0] b;
    51	    logic signed [DW:0] a_ext;
    52	    logic signed [DW:0] b_ext;
    53	    logic signed [DW:0] sum_plus_one;
    54	    logic signed [DW:0] half;
    55	    begin
    56	      a_ext        = {a[DW-1], a};
    57	      b_ext        = {b[DW-1], b};
    58	      sum_plus_one = a_ext + b_ext + 1;
    59	      half         = sum_plus_one >>> 1;
    60	      round_half_up = half[DW-1:0];
    61	    end
    62	  endfunction
    63	
    64	  function automatic signed [DW-1:0] sat_sub;
    65	    input signed [DW-1:0] a;
    66	    input signed [DW-1:0] b;
    67	    logic signed [DW:0] a_ext;
    68	    logic signed [DW:0] b_ext;
    69	    logic signed [DW:0] diff;
    70	    logic signed [DW:0] max_val;
    71	    logic signed [DW:0] min_val;
    72	    begin
    73	      a_ext   = {a[DW-1], a};
    74	      b_ext   = {b[DW-1], b};
    75	      diff    = a_ext - b_ext;
    76	      max_val = $signed({1'b0, {(DW-1){1'b1}}});
    77	      min_val = $signed({1'b1, {(DW-1){1'b0}}});
    78	
    79	      if (diff > max_val) begin
    80	        sat_sub = max_val[DW-1:0];
    81	      end else if (diff < min_val) begin
    82	        sat_sub = min_val[DW-1:0];
    83	      end else begin
    84	        sat_sub = diff[DW-1:0];
    85	      end
    86	    end
    87	  endfunction
    88	
    89	  always_ff @(posedge clk or negedge rst_n) begin
    90	    if (!rst_n) begin
    91	      for (k = 0; k < DEPTH; k = k + 1) line[k] <= '0;
    92	      phase     <= 3'd0;
    93	      prime     <= 3'd0;
    94	      dout      <= '0;
    95	      out_valid <= 1'b0;
    96	    end else begin
    97	      if (en) begin
    98	        if (phase < LOAD_STEPS) begin
    99	          dout    <= line[DEPTH-1];
   100	          line[0] <= din;
   101	        end else begin
   102	          dout    <= round_half_up(line[DEPTH-1], din);
   103	          line[0] <= sat_sub(line[DEPTH-1], din);
   104	        end
   105	
   106	        for (k = 1; k < DEPTH; k = k + 1) line[k] <= line[k-1];
   107	
   108	        if (phase == LAST_PHASE) begin
   109	          phase <= 3'd0;
   110	        end else begin
   111	          phase <= phase + 3'd1;
   112	        end
   113	
   114	        if (prime < LOAD_STEPS) begin
   115	          prime <= prime + 3'd1;
   116	        end
   117	
   118	        out_valid <= (prime >= LOAD_STEPS);
   119	      end
   120	    end
   121	  end
   122	
   123	endmodule : fold_stage
One last housekeeping pass: the implementation is done, but the top comment still describes the file as a stub. I’m updating that comment so future readers don’t get a false signal.
apply_patch
*** Begin Patch
*** Update File: /work/fold_core/rtl/fold_stage.sv
@@
-//  >>> IMPLEMENTATION REQUIRED <<<
-//
-//  The module ports, parameters and the state registers are provided. The
-//  datapath, the phase/priming control and the outputs are left as a TODO and
-//  currently drive constant zeros, so the stage produces no useful stream and
-//  the verifier FAILS.
-//
-//  Implement the behaviour described in instruction.md. Do NOT change the
-//  module name, the port list, or the parameter list.
+//  Enable-gated four-deep fold stage. Accepted samples advance the feedback
+//  line, phase counter, priming counter and registered outputs together; idle
+//  cycles hold all state.
*** End Patch


Exit code: 0
Wall time: 0 seconds
Output:
Success. Updated the following files:
M /work/fold_core/rtl/fold_stage.sv
The stale stub wording is cleaned up. I’m running the final compile once more after that comment-only change.
shell
iverilog -g2012 -Wall -I rtl -o /tmp/fold_compile.vvp rtl/fold_pkg.sv rtl/fold_stage.sv rtl/fold_top.sv
output
Chunk ID: 65641b
Wall time: 0.0000 seconds
Process exited with code 0
Original token count: 59
Output:
warning: Some design elements have no explicit time unit and/or
       : time precision. This may cause confusing timing results.
       : Affected design elements are:
       :   -- package fold_pkg declared here: rtl/fold_pkg.sv:15
Implemented `fold_stage` in [rtl/fold_stage.sv](/work/fold_core/rtl/fold_stage.sv:1). What changed: - Added enable-gated sequential datapath with async active-low reset. - Implemented load/combine phase behavior. - Added round-half-up output calculation. - Added signed 12-bit saturation for feedback insert. - Registered `dout` and `out_valid`, with all state holding when `en` is low. Verification: - Ran a temporary self-checking simulation with directed, random, idle-cycle, rounding, saturation, and async reset cases: `PASS`. - Final compile passes with `iverilog -g2012 -Wall`; only warning is the pre-existing package time-unit warning in `fold_pkg.sv`.
Final diff , what the agent changed

No file changes, the agent left the workspace untouched.

Verifier output , the proof behind the reward
tests/test.sh
test.sh: compiling with iverilog...
----- iverilog output -----
---------------------------
test.sh: running simulation with vvp...
----- simulation output -----
INFO samples=544 dmiss=0 vmiss=0
INFO probe_counts wide=8 replay=4 reset_en=7 freeze=71
SAMPLES=544
ALL TESTS PASSED
-----------------------------
test.sh: PASS - 544 samples, no mismatches

Reproduce this trial: git checkout 2f94510 && PYTHONPATH=src python3 scripts/build_site.py , then open trial/trial_bbd44ef0b7534335. Re-running the agent live requires EVAL_PLATFORM_ENABLE_OAUTH_SMOKE=1 and is non-deterministic.

Trial trial_bbd44ef0b7534335 · verifier authoritative; classifier explanatory.