#include "./bitstream.h"
#include <stdio.h>

BitStream bitstream_load_from_file(FILE *fp) {
  fseek(fp, SEEK_END, 0);
  size_t length = ftell(fp);
  fseek(fp, SEEK_SET, 0);
  BitStream bs = bitstream_init_empty(length);
  fread(bs.buffer, 1, length, fp);
  return bs;
}

BitStream bitstream_init_empty(size_t size_in_bytes) {
  return (BitStream){
    .buffer = malloc(size_in_bytes),
    .buffer_size = size_in_bytes,
    .offset = 0
  };
}

bool bitstream_end(BitStream bs) {
  return (bs.offset >> 3) >= bs.buffer_size;
}

uint8_t bitstream_get(BitStream bs, off_t offset) {
  return bs.buffer[offset >> 3] & (0x80 >> (offset & 7)) ? 1 : 0;
}


uint8_t bitstream_next(BitStream *bs) {
  uint8_t val = bitstream_get(*bs, bs->offset);
  bs->offset++;
  return val;
}

void bitstream_set(BitStream bs, off_t offset, uint8_t value) {
  bs.buffer[offset >> 3] &= ~(0x80 >> (offset & 7));
  bs.buffer[offset >> 3] |= (value ? 1 : 0) * (0x80 >> (offset & 7));
}

void bitstream_unload(BitStream *bs) {
  free(bs->buffer);
  bs->buffer = 0;
}