heatshrink_encoder *heatshrink_encoder_alloc(uint8_t window_sz2,
uint8_t lookahead_sz2) {
if ((window_sz2 < HEATSHRINK_MIN_WINDOW_BITS) ||
(window_sz2 > HEATSHRINK_MAX_WINDOW_BITS) ||
(lookahead_sz2 < HEATSHRINK_MIN_LOOKAHEAD_BITS) ||
(lookahead_sz2 >= window_sz2)) {
return NULL;
}
/* Note: 2 * the window size is used because the buffer needs to fit
* (1 << window_sz2) bytes for the current input, and an additional
* (1 << window_sz2) bytes for the previous buffer of input, which
* will be scanned for useful backreferences. */
size_t buf_sz = (2 << window_sz2);
heatshrink_encoder *hse = HEATSHRINK_MALLOC(sizeof(*hse) + buf_sz);
if (hse == NULL) { return NULL; }
hse->window_sz2 = window_sz2;
hse->lookahead_sz2 = lookahead_sz2;
heatshrink_encoder_reset(hse);
#if HEATSHRINK_USE_INDEX
size_t index_sz = buf_sz*sizeof(uint16_t);
hse->search_index = HEATSHRINK_MALLOC(index_sz + sizeof(struct hs_index));
if (hse->search_index == NULL) {
HEATSHRINK_FREE(hse, sizeof(*hse) + buf_sz);
return NULL;
}
hse->search_index->size = index_sz;
#endif
LOG("-- allocated encoder with buffer size of %zu (%u byte input size)\n",
buf_sz, get_input_buffer_size(hse));
return hse;
}
heatshrink_decoder *heatshrink_decoder_alloc(uint16_t input_buffer_size,
uint8_t window_sz2,
uint8_t lookahead_sz2) {
if ((window_sz2 < HEATSHRINK_MIN_WINDOW_BITS) ||
(window_sz2 > HEATSHRINK_MAX_WINDOW_BITS) ||
(input_buffer_size == 0) ||
(lookahead_sz2 < HEATSHRINK_MIN_LOOKAHEAD_BITS) ||
(lookahead_sz2 > window_sz2)) {
return NULL;
}
size_t buffers_sz = (1 << window_sz2) + input_buffer_size;
size_t sz = sizeof(heatshrink_decoder) + buffers_sz;
heatshrink_decoder *hsd = HEATSHRINK_MALLOC(sz);
if (hsd == NULL) { return NULL; }
hsd->input_buffer_size = input_buffer_size;
hsd->window_sz2 = window_sz2;
hsd->lookahead_sz2 = lookahead_sz2;
heatshrink_decoder_reset(hsd);
LOG("-- allocated decoder with buffer size of %zu (%zu + %u + %u)\n",
sz, sizeof(heatshrink_decoder), (1 << window_sz2), input_buffer_size);
return hsd;
}
