sintables.c

#include <inttypes.h>
#include <math.h>
#include <unistd.h>
#include <stdio.h>

#ifndef FREQ
#define FREQ 44100
#endif

#ifndef CHANNELS
#define CHANNELS 2
#endif

#ifndef SAMPLE_WIDTH
#define SAMPLE_WIDTH 16
#endif

int main()
{
        unsigned data_size = 8 * 3 * FREQ * CHANNELS * (SAMPLE_WIDTH / 8);
        struct riff {
                char id[4];
                uint32_t sz;
                uint32_t fmt;

                char sub1[4];
                uint32_t sz1;
                uint16_t au_fmt;
                uint16_t channels;
                uint32_t sample_rate;
                uint32_t byte_rate;
                uint16_t block_align;
                uint16_t bits_per_sample;

                char sub2[4];
                uint32_t sz2;
        } hdr = {
                .id = "RIFF",
                .sz = data_size + 0x24,
                .fmt = 0x45564157,

                .sub1 = "fmt ",
                .sz1 = 0x10,
                .au_fmt = 1,
                .channels = CHANNELS,
                .sample_rate = FREQ,
                .byte_rate = FREQ * CHANNELS * SAMPLE_WIDTH / 8,
                .block_align = CHANNELS * SAMPLE_WIDTH / 8,
                .bits_per_sample = SAMPLE_WIDTH,

                .sub2 = "data",
                .sz2 = data_size,
        };

        unsigned freq;
        const unsigned amp = 1 << (SAMPLE_WIDTH - 2);

        write(STDOUT_FILENO, &hdr, sizeof(hdr));
        for (freq = 440; freq < FREQ / 2; freq *= 2) {
                unsigned i;
                for (i = 0; i < 3 * FREQ; ++i) {
                        int32_t v[2] = {
                                amp * sin((2 * 3.141592653589793 * freq * i) / FREQ),
                                0x55555555,
                        };
                        write(STDOUT_FILENO, v, SAMPLE_WIDTH / 8);
                        write(STDOUT_FILENO, v + 1, SAMPLE_WIDTH / 8);
                }
        }
        return 0;
}