static HSD_state st_yield_backref(heatshrink_decoder *hsd,
output_info *oi) {
size_t count = oi->buf_size - *oi->output_size;
if (count > 0) {
size_t i = 0;
if (hsd->output_count < count) count = hsd->output_count;
uint8_t *buf = &hsd->buffers[HEATSHRINK_DECODER_INPUT_BUFFER_SIZE(hsd)];
uint16_t mask = (1 << HEATSHRINK_DECODER_WINDOW_BITS(hsd)) - 1;
uint16_t neg_offset = hsd->output_index;
LOG("-- emitting %zu bytes from -%u bytes back\n", count, neg_offset);
ASSERT(neg_offset <= mask + 1);
ASSERT(count <= (size_t)(1 << BACKREF_COUNT_BITS(hsd)));
for (i=0; i<count; i++) {
uint8_t c = buf[(hsd->head_index - neg_offset) & mask];
push_byte(hsd, oi, c);
buf[hsd->head_index & mask] = c;
hsd->head_index++;
LOG(" -- ++ 0x%02x\n", c);
}
hsd->output_count -= count;
if (hsd->output_count == 0) { return HSDS_TAG_BIT; }
}
return HSDS_YIELD_BACKREF;
}
static HSD_state st_input_available(heatshrink_decoder *hsd) {
uint32_t bits = get_bits(hsd, 1); // get tag bit
if (bits) {
return HSDS_YIELD_LITERAL;
} else if (HEATSHRINK_DECODER_WINDOW_BITS(hsd) > 8) {
return HSDS_BACKREF_INDEX_MSB;
} else {
hsd->output_index = 0;
return HSDS_BACKREF_INDEX_LSB;
}
}
void heatshrink_decoder_reset(heatshrink_decoder *hsd) {
size_t buf_sz = 1 << HEATSHRINK_DECODER_WINDOW_BITS(hsd);
size_t input_sz = HEATSHRINK_DECODER_INPUT_BUFFER_SIZE(hsd);
memset(hsd->buffers, 0, buf_sz + input_sz);
hsd->state = HSDS_TAG_BIT;
hsd->input_size = 0;
hsd->input_index = 0;
hsd->bit_index = 0x00;
hsd->current_byte = 0x00;
hsd->output_count = 0;
hsd->output_index = 0;
hsd->head_index = 0;
}
static HSD_state st_yield_literal(heatshrink_decoder *hsd,
output_info *oi) {
/* Emit a repeated section from the window buffer, and add it (again)
* to the window buffer. (Note that the repetition can include
* itself.)*/
if (*oi->output_size < oi->buf_size) {
uint32_t byte = get_bits(hsd, 8);
if (byte == NO_BITS) { return HSDS_YIELD_LITERAL; } /* out of input */
uint8_t *buf = &hsd->buffers[HEATSHRINK_DECODER_INPUT_BUFFER_SIZE(hsd)];
uint16_t mask = (1 << HEATSHRINK_DECODER_WINDOW_BITS(hsd)) - 1;
uint8_t c = byte & 0xFF;
LOG("-- emitting literal byte 0x%02x ('%c')\n", c, isprint(c) ? c : '.');
buf[hsd->head_index++ & mask] = c;
push_byte(hsd, oi, c);
return HSDS_CHECK_FOR_MORE_INPUT;
} else {
return HSDS_YIELD_LITERAL;
}
}
