tyler
849306d65e
Build system - Add a single hand-written Makefile (GNU make + gcc, pure C). Builds raylib from vendored source and links rspektrum with no premake/lua. Targets: all/run/test/bench/clean; release default, DEBUG=1 for debug; ARCH overridable (defaults to -march=x86-64-v3). - Remove premake entirely: rspektrum.make, raylib.make, build/premake5* binaries, build/premake5.lua, build/ecc/*. The generated top-level Makefile was gitignored, so hand-edits to it were silently lost. - Vendor raylib src/ into the repo (was gitignored -> fresh clones could not build). Commit only src/ (~16MB); examples/projects stay local. Verified: a build from the git-tracked tree alone succeeds offline. - Release flags bumped to -O3 -ffast-math with a portable arch baseline (x86-64-v3 = AVX2+FMA on x64, SSE2 on x86). Confirmed FMA/AVX codegen in fft.o. FFT optimization (src/fft.c) - Precompute twiddle factors and the bit-reversal permutation once per size, cached as a small plan table (FFTW's idea, lightweight). Removes the per-butterfly cexpf() and per-element bit-twiddling that dominated. - 3.6x faster on the mlnl_samples.wav STFT workload (2048-pt, -O2 same flags both sides): 81us -> 22us per FFT. With the new -O3/-ffast-math/ AVX2 release flags stacked: ~15us (5.5x vs the old -O2 baseline). - Verified vs a double-precision reference DFT: 1e-6 relative error, round-trip 2.4e-7. Drop-in: same FFT() signature. Tests/bench (bench/) - fft_verify.c: FFT vs reference DFT + round-trip check (make test). - fft_bench.c: times the real STFT workload (make bench). Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
97 lines
3.5 KiB
C
97 lines
3.5 KiB
C
// fft_bench.c - Isolated benchmark of FFT() over the real mlnl_samples.wav STFT
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// workload (2048-pt forward transforms, hop = fftSize/4, 75% overlap).
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//
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// Build: cc -O2 -march=native fft_bench.c ../src/fft.c -lm -o fft_bench
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// (link whichever fft.c you want to measure; -DFFT_BENCH_REPS=N to override reps)
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <stdint.h>
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#include <complex.h>
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#include <math.h>
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#include <time.h>
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#include "../src/fft.h"
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#define FFT_SIZE 2048
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#define HOP_RATIO 4
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#ifndef FFT_BENCH_REPS
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#define FFT_BENCH_REPS 50 // repeat the whole STFT pass this many times
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#endif
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// Minimal WAV loader: 16-bit PCM, returns mono float frames (first channel).
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static float* load_wav(const char* path, int* outN) {
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FILE* f = fopen(path, "rb");
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if (!f) { perror("open wav"); exit(1); }
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fseek(f, 0, SEEK_END); long sz = ftell(f); fseek(f, 0, SEEK_SET);
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uint8_t* buf = malloc(sz);
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if (fread(buf, 1, sz, f) != (size_t)sz) { fprintf(stderr, "read fail\n"); exit(1); }
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fclose(f);
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// Walk RIFF chunks to find fmt + data.
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int channels = 1, bits = 16; uint32_t dataOff = 0, dataLen = 0;
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uint32_t p = 12; // skip RIFF....WAVE
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while (p + 8 <= (uint32_t)sz) {
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uint32_t cid; memcpy(&cid, buf + p, 4);
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uint32_t clen; memcpy(&clen, buf + p + 4, 4);
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if (memcmp(buf + p, "fmt ", 4) == 0) {
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memcpy(&channels, buf + p + 8 + 2, 2);
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memcpy(&bits, buf + p + 8 + 14, 2);
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} else if (memcmp(buf + p, "data", 4) == 0) {
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dataOff = p + 8; dataLen = clen; break;
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}
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p += 8 + clen + (clen & 1);
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}
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if (!dataOff || bits != 16) { fprintf(stderr, "need 16-bit PCM wav\n"); exit(1); }
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int bytesPerSample = 2 * channels;
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int n = dataLen / bytesPerSample;
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float* out = malloc(n * sizeof(float));
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const int16_t* pcm = (const int16_t*)(buf + dataOff);
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for (int i = 0; i < n; i++) out[i] = pcm[i * channels] / 32768.0f;
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free(buf);
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*outN = n;
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return out;
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}
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static double now_sec(void) {
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struct timespec ts; clock_gettime(CLOCK_MONOTONIC, &ts);
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return ts.tv_sec + ts.tv_nsec * 1e-9;
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}
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int main(int argc, char** argv) {
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const char* path = argc > 1 ? argv[1] : "../mlnl_samples.wav";
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int n; float* samples = load_wav(path, &n);
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int hop = FFT_SIZE / HOP_RATIO;
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int frames = (n - FFT_SIZE) / hop + 1;
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if (frames < 1) { fprintf(stderr, "too short\n"); return 1; }
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float complex* in = malloc(FFT_SIZE * sizeof(float complex));
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float complex* out = malloc(FFT_SIZE * sizeof(float complex));
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// Hann-windowed frames, exactly like stft.c feeds FFT().
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double checksum = 0.0;
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double t0 = now_sec();
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for (int rep = 0; rep < FFT_BENCH_REPS; rep++) {
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for (int fr = 0; fr < frames; fr++) {
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int off = fr * hop;
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for (int i = 0; i < FFT_SIZE; i++) {
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float w = 0.5f - 0.5f * cosf(2.0f * (float)M_PI * i / (FFT_SIZE - 1));
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in[i] = samples[off + i] * w + 0.0f * I;
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}
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FFT(in, out, FFT_SIZE, false);
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checksum += crealf(out[1]) + cimagf(out[1]);
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}
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}
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double t1 = now_sec();
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long long totalFFTs = (long long)frames * FFT_BENCH_REPS;
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double secs = t1 - t0;
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printf("samples=%d frames=%d reps=%d total_FFTs=%lld\n",
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n, frames, FFT_BENCH_REPS, totalFFTs);
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printf("elapsed=%.4f s per-FFT=%.3f us FFTs/s=%.0f\n",
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secs, secs / totalFFTs * 1e6, totalFFTs / secs);
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printf("checksum=%.6f (anti-DCE)\n", checksum);
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return 0;
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}
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