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#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <inttypes.h>
#define MAGIC 0x7d53b605
#define MIN_REF_LEN 5
#define MAX_REF 127 + MIN_REF_LEN
typedef struct {
unsigned size;
unsigned char *data;
unsigned real_size;
} file_data_t;
typedef struct __attribute ((packed)) {
uint32_t magic;
uint32_t size;
uint32_t unpacked_size;
uint32_t sample_rate;
} snd_header_t;
file_data_t *read_file(char *name);
void add_data(file_data_t *d, void *buffer, unsigned size);
void write_data(file_data_t *d, char *name);
void compr(file_data_t *fd, file_data_t *fd_compr);
unsigned find_longest(unsigned char *data, unsigned len, unsigned start, unsigned *ofs);
int main(int argc, char **argv)
{
file_data_t *fd, fd_compr = { }, fd_samples = { };
snd_header_t sh;
unsigned sample_rate;
if(argc != 3) return 1;
fd = read_file(argv[1]);
if(fd->size <= 44) return 1;
if(
*((unsigned *) (fd->data + 0)) != 0x46464952 ||
*((unsigned *) (fd->data + 8)) != 0x45564157 ||
*((short *) (fd->data + 20)) != 1 ||
*((short *) (fd->data + 34)) != 8 ||
*((short *) (fd->data + 22)) != 1
) {
fprintf(stderr, "invalid data, expecting 8bit mono wav (ms pcm) file\n");
return 3;
}
sample_rate = *((unsigned *) (fd->data + 24));
printf("%s: %u Hz, %u samples\n", argv[1], sample_rate, fd->size - 44);
add_data(&fd_samples, fd->data + 44, fd->size - 44);
sh.magic = MAGIC;
sh.unpacked_size = fd_samples.size;
sh.sample_rate = sample_rate;
add_data(&fd_compr, &sh, sizeof sh);
compr(&fd_samples, &fd_compr);
sh.size = fd_compr.size - sizeof (snd_header_t);
memcpy(fd_compr.data, &sh, sizeof (snd_header_t));
write_data(&fd_compr, argv[2]);
return 0;
}
file_data_t *read_file(char *name)
{
file_data_t *fd;
FILE *f;
fd = calloc(1, sizeof *fd);
if(!name) return fd;
f = fopen(name, "r");
if(!f) { perror(name); return fd; }
if(fseek(f, 0, SEEK_END)) {
perror(name);
exit(30);
}
fd->size = fd->real_size = ftell(f);
if(fseek(f, 0, SEEK_SET)) {
perror(name);
exit(30);
}
if(fd->size) {
fd->data = calloc(1, fd->size);
if(!fd->data) {
fprintf(stderr, "malloc failed\n");
exit(30);
}
}
if(fread(fd->data, 1, fd->size, f) != fd->size) {
perror(name);
exit(30);
}
fclose(f);
return fd;
}
void add_data(file_data_t *d, void *buffer, unsigned size)
{
if(!size || !d || !buffer) return;
if(d->size + size > d->real_size) {
d->real_size = d->size + size + 0x1000;
d->data = realloc(d->data, d->real_size);
if(!d->data) d->real_size = 0;
}
if(d->size + size <= d->real_size) {
memcpy(d->data + d->size, buffer, size);
d->size += size;
}
else {
fprintf(stderr, "Oops, out of memory? Aborted.\n");
exit(10);
}
}
void write_data(file_data_t *d, char *name)
{
FILE *f;
f = strcmp(name, "-") ? fopen(name, "w") : stdout;
if(!f) {
perror(name);
return;
}
if(fwrite(d->data, d->size, 1, f) != 1) {
perror(name);
exit(3);
}
fclose(f);
}
void compr(file_data_t *fd, file_data_t *fd_compr)
{
unsigned u, v, l, ofs;
unsigned char uc;
if(!fd->size) return;
for(u = 0; u < fd->size; u++) {
if(fd->data[u] == 0xff) fd->data[u] = 0xfe;
}
// printf("%5u: %02x\n", fd->size, fd->data[0]);
add_data(fd_compr, fd->data, 1);
for(u = 1; u < fd->size; ) {
l = find_longest(fd->data, fd->size, u, &ofs);
// printf("%u: %u bytes @ %u\n", u, l, ofs);
if(l >= MIN_REF_LEN) {
// printf("%5u: %u bytes @ %u\n", fd->size, l, ofs);
v = (ofs << 7) + l - MIN_REF_LEN;
uc = 0xff; add_data(fd_compr, &uc, 1);
uc = v; add_data(fd_compr, &uc, 1);
uc = v >> 8; add_data(fd_compr, &uc, 1);
uc = v >> 16; add_data(fd_compr, &uc, 1);
u += l;
}
else {
// printf("%5u: %02x\n", fd->size, fd->data[u]);
add_data(fd_compr, fd->data + u, 1);
u++;
}
}
}
unsigned find_longest(unsigned char *data, unsigned len, unsigned start, unsigned *ofs)
{
unsigned l;
unsigned char *p, *p1;
p = data;
l = MIN_REF_LEN;
for(;;) {
p1 = memmem(p, data + start + l - 1 - p, data + start, l);
if(!p1) break;
p = p1;
l++;
if(l > MAX_REF) break;
}
l--;
if(l < MIN_REF_LEN) {
*ofs = 0;
return 0;
}
*ofs = p - data;
return l;
}
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