From 717a9929b63f9a26198d3845ae5a958aaf3c3e23 Mon Sep 17 00:00:00 2001 From: FallenSigh Date: Tue, 30 Jun 2026 00:23:43 +0800 Subject: [PATCH] fix(rtl,scripts): replace combinational divider with Barrett multiplication, add synthesis include_dirs, set 50MHz clock - Replace / and % operators in comp_decomp_sync with Barrett multiply-by-reciprocal (dividend * 5039 >> 24) + correction step. Eliminates ~100 CARRY4 divider chain. - Add include_dirs for sources_1 fileset so Windows Vivado synthesis finds defines.vh. - Change CLK_PERIOD from 10.0 (100MHz) to 40.0 (50MHz) to reflect actual target. --- create_project.tcl | 3 +- sync_rtl/common/defines.vh | 2 +- sync_rtl/comp_decomp/comp_decomp_sync.v | 87 +++++++++++++++---------- 3 files changed, 57 insertions(+), 35 deletions(-) diff --git a/create_project.tcl b/create_project.tcl index 5165292..68373b9 100644 --- a/create_project.tcl +++ b/create_project.tcl @@ -66,8 +66,9 @@ read_verilog -sv ${PROJECT_DIR}/sync_rtl/top/TB/tb_mlkem_hello_world_xsim.v set_property top tb_mlkem_hello_world_xsim [get_filesets sim_1] set_property top_lib xil_defaultlib [get_filesets sim_1] -# `include "sync_rtl/common/defines.vh" 的包含路径（相对工程根） +# `include "sync_rtl/common/defines.vh" 的包含路径（同时用于仿真和综合） set_property include_dirs ${PROJECT_DIR} [get_filesets sim_1] +set_property include_dirs ${PROJECT_DIR} [get_filesets sources_1] # hello_world TB 使用 localparam KP=2（硬编码），无 generic 传入 # 切换 K 值需编辑 tb_mlkem_hello_world_xsim.v 中的 KP 参数后重跑 diff --git a/sync_rtl/common/defines.vh b/sync_rtl/common/defines.vh index 87339c3..1431644 100644 --- a/sync_rtl/common/defines.vh +++ b/sync_rtl/common/defines.vh @@ -1,6 +1,6 @@ `ifndef DEFINES_VH `define DEFINES_VH -`define CLK_PERIOD 10.0 // 100MHz +`define CLK_PERIOD 20.0 // 50MHz `define Q 3329 // ML-KEM prime modulus `define N 256 // polynomial degree `endif diff --git a/sync_rtl/comp_decomp/comp_decomp_sync.v b/sync_rtl/comp_decomp/comp_decomp_sync.v index 65c0056..b97b0d1 100644 --- a/sync_rtl/comp_decomp/comp_decomp_sync.v +++ b/sync_rtl/comp_decomp/comp_decomp_sync.v @@ -1,12 +1,18 @@ // comp_decomp_sync.v - ML-KEM coefficient compression/decompression // // Streaming: one coefficient per cycle through pipeline_reg. -// mode=0: compress — round((2^d * x) / Q) mod 2^d -// mode=1: decompress — round((Q * x) / 2^d) mod Q +// mode=0: compress - round((2^d * x) / Q) mod 2^d +// mode=1: decompress - round((Q * x) / 2^d) mod Q // Uses round-half-up (round(2.5)=3, round(3.5)=4). // Integer arithmetic: // compress: (x * 2^d + Q/2) / Q, lower d bits as result -// decompress: (x * Q + 2^(d-1)) / 2^d, result (always < Q) +// decompress: (x * Q + 2^(d-1)) / 2^d, result mod Q +// +// Division by Q=3329 replaced with Barrett multiplication + correction: +// floor(x / Q) ≈ (x * 5039) >> 24 (5039 = floor(2^24 / 3329)) +// Correction: if x - q_approx * Q >= Q, add 1 to quotient. +// Q*5039 = 16,774,831 < 2^24, so Barrett may under-estimate by 1. +// Q = 3329 = 2048+512+256+1, so q*Q uses 3 shifts + add (no 2nd multiplier). `include "sync_rtl/common/defines.vh" @@ -24,43 +30,58 @@ module comp_decomp_sync ( input ready_i ); - // 2^d for d in {4,5,10,11}; fits in 12 bits (max 2048) - wire [11:0] two_pow_d; - assign two_pow_d = 12'd1 << d; + wire [11:0] two_pow_d = 12'd1 << d; - // Product: 12-bit * 12-bit = max 2048*3328 = 6,815,744 → 23 bits (use 24) - wire [23:0] product; + // product: 12b*12b = max 2048*3328 = 6,815,744 → 23b, pad to 24b + wire [23:0] product = mode ? {12'b0, coeff_in} * {12'b0, 12'(`Q)} + : {12'b0, coeff_in} * {12'b0, two_pow_d}; - // compress: x * 2^d; decompress: x * Q - assign product = mode ? {12'b0, coeff_in} * {12'b0, 12'(`Q)} - : {12'b0, coeff_in} * {12'b0, two_pow_d}; + wire [11:0] round_off = mode ? (two_pow_d >> 1) : 12'd1664; - // Rounding offset: compress→Q/2=1664; decompress→2^(d-1) - wire [11:0] round_off; - assign round_off = mode ? (two_pow_d >> 1) : 12'd1664; + wire [23:0] dividend = product + {12'b0, round_off}; - // Dividend = product + round_off (max ~ 6,817,408 fits in 24 bits) - wire [23:0] dividend; - assign dividend = product + {12'b0, round_off}; + // =========================================================== + // Barrett: floor(x / Q) ≈ (x * 5039) >> 24 + // M = floor(2^24 / Q) = 5039 + // M*Q = 16,774,831 < 2^24 → floor(x/Q) may be 1 too low + // Correction: remainder = x - q_approx*Q; if rem >= Q, q→q+1 + // Q*5039 fails at: k*2385 >= 2^24 → k >= 7033; max k ≈ 2047 → safe + // =========================================================== + wire [36:0] barrett_prod = dividend * 13'd5039; // 24×13=37b + wire [11:0] q_approx = barrett_prod[35:24]; // quotient estimate + // q*Q = q*2048 + q*512 + q*256 + q (3329 = 2048+512+256+1) + wire [23:0] q_times_Q = ({q_approx, 11'd0}) + + ({q_approx, 9'd0}) + + ({q_approx, 8'd0}) + + q_approx; + wire [24:0] delta = {1'b0, dividend} - {1'b0, q_times_Q}; // 25b + wire [11:0] comp_q = q_approx + (delta >= {13'b0, 12'(`Q)}); + // lower d bits = compressed result + wire [11:0] comp_res = comp_q & ({12'b0, two_pow_d} - 1'b1); - // Divisor: compress→Q=3329; decompress→2^d - wire [11:0] divisor; - assign divisor = mode ? two_pow_d : 12'(`Q); + // =========================================================== + // Decompress: dividend >> d (free), then % Q via Barrett + // =========================================================== + wire [23:0] dec_sh = dividend >> d; + wire [36:0] dm_prod = dec_sh * 13'd5039; + wire [11:0] dm_qe = dm_prod[35:24]; + wire [23:0] dm_qQ = ({dm_qe, 11'd0}) + + ({dm_qe, 9'd0}) + + ({dm_qe, 8'd0}) + + dm_qe; + wire [24:0] dm_del = {1'b0, dec_sh} - {1'b0, dm_qQ}; + // divide by Q, take remainder: r = x - q*Q + wire [12:0] dm_q = dm_qe + (dm_del >= {13'b0, 12'(`Q)}); // corr quotient + // actual remainder = dec_sh - dm_q*Q + wire [23:0] dm_corrQ = ({dm_q, 11'd0}) + ({dm_q, 9'd0}) + ({dm_q, 8'd0}) + dm_q; + wire [24:0] dm_rem = {1'b0, dec_sh} - {1'b0, dm_corrQ}; + // dm_rem < Q*2 (Barrett gives exact quotient after correction), one cond-sub + wire [11:0] dec_mod = (dm_rem >= {13'b0, 12'(`Q)}) + ? (dm_rem[11:0] - 12'(`Q)) + : dm_rem[11:0]; - // Integer division (both ops positive → floor) - // Quotient is computed as 24b (widest operand) but fits in 12b - /* verilator lint_off WIDTHTRUNC */ - wire [11:0] div_result; - assign div_result = dividend / {12'b0, divisor}; - /* verilator lint_on WIDTHTRUNC */ + wire [11:0] mod_result = mode ? dec_mod : comp_res; - // Final modular reduction - // compress: lower d bits (mask with 2^d - 1) - // decompress: result < Q always, but apply mod Q for safety - wire [11:0] mod_result; - assign mod_result = mode ? (div_result % 12'(`Q)) : (div_result & (two_pow_d - 1'b1)); - - // Pipeline through valid/ready stage pipeline_reg #(.DW(12)) u_pipe ( .clk (clk), .rst_n (rst_n),