HSE_sink_res heatshrink_encoder_sink(heatshrink_encoder *hse,
uint8_t *in_buf, size_t size, size_t *input_size) {
if ((hse == NULL) || (in_buf == NULL) || (input_size == NULL)) {
return HSER_SINK_ERROR_NULL;
}
/* Sinking more content after saying the content is done, tsk tsk */
if (is_finishing(hse)) { return HSER_SINK_ERROR_MISUSE; }
/* Sinking more content before processing is done */
if (hse->state != HSES_NOT_FULL) { return HSER_SINK_ERROR_MISUSE; }
uint16_t write_offset = get_input_offset(hse) + hse->input_size;
uint16_t ibs = get_input_buffer_size(hse);
uint16_t rem = ibs - hse->input_size;
uint16_t cp_sz = rem < size ? rem : size;
memcpy(&hse->buffer[write_offset], in_buf, cp_sz);
*input_size = cp_sz;
hse->input_size += cp_sz;
LOG("-- sunk %u bytes (of %zu) into encoder at %d, input buffer now has %u\n",
cp_sz, size, write_offset, hse->input_size);
if (cp_sz == rem) {
LOG("-- internal buffer is now full\n");
hse->state = HSES_FILLED;
}
return HSER_SINK_OK;
}
static HSE_state ICACHE_FLASH_ATTR st_step_search(heatshrink_encoder *hse) {
uint16_t window_length = get_input_buffer_size(hse);
uint16_t lookahead_sz = get_lookahead_size(hse);
uint16_t msi = hse->match_scan_index;
LOG("## step_search, scan @ +%d (%d/%d), input size %d\n",
msi, hse->input_size + msi, 2*window_length, hse->input_size);
bool fin = is_finishing(hse);
if (msi >= hse->input_size - (fin ? 0 : lookahead_sz)) {
/* Current search buffer is exhausted, copy it into the
* backlog and await more input. */
LOG("-- end of search @ %d, saving backlog\n", msi);
return HSES_SAVE_BACKLOG;
}
uint16_t input_offset = get_input_offset(hse);
uint16_t end = input_offset + msi;
uint16_t start = 0;
if (backlog_is_filled(hse)) { /* last WINDOW_LENGTH bytes */
start = end - window_length + 1;
} else if (backlog_is_partial(hse)) { /* clamp to available data */
start = end - window_length + 1;
if (start < lookahead_sz) { start = lookahead_sz; }
} else { /* only scan available input */
start = input_offset;
}
uint16_t max_possible = lookahead_sz;
if (hse->input_size - msi < lookahead_sz) {
max_possible = hse->input_size - msi;
}
uint16_t match_length = 0;
uint16_t match_pos = find_longest_match(hse,
start, end, max_possible, &match_length);
if (match_pos == MATCH_NOT_FOUND) {
LOG("ss Match not found\n");
hse->match_scan_index++;
hse->flags |= FLAG_HAS_LITERAL;
hse->match_length = 0;
return HSES_YIELD_TAG_BIT;
} else {
LOG("ss Found match of %d bytes at %d\n", match_length, match_pos);
hse->match_pos = match_pos;
hse->match_length = match_length;
ASSERT(match_pos < 1 << hse->window_sz2 /*window_length*/);
return HSES_YIELD_TAG_BIT;
}
}
static HSE_state st_step_search(heatshrink_encoder *hse) {
uint16_t window_length = get_input_buffer_size(hse);
uint16_t lookahead_sz = get_lookahead_size(hse);
uint16_t msi = hse->match_scan_index;
LOG("## step_search, scan @ +%d (%d/%d), input size %d\n",
msi, hse->input_size + msi, 2*window_length, hse->input_size);
bool fin = is_finishing(hse);
if (msi > hse->input_size - (fin ? 1 : lookahead_sz)) {
/* Current search buffer is exhausted, copy it into the
* backlog and await more input. */
LOG("-- end of search @ %d\n", msi);
return fin ? HSES_FLUSH_BITS : HSES_SAVE_BACKLOG;
}
uint16_t input_offset = get_input_offset(hse);
uint16_t end = input_offset + msi;
uint16_t start = end - window_length;
uint16_t max_possible = lookahead_sz;
if (hse->input_size - msi < lookahead_sz) {
max_possible = hse->input_size - msi;
}
uint16_t match_length = 0;
uint16_t match_pos = find_longest_match(hse,
start, end, max_possible, &match_length);
if (match_pos == MATCH_NOT_FOUND) {
LOG("ss Match not found\n");
hse->match_scan_index++;
hse->match_length = 0;
return HSES_YIELD_TAG_BIT;
} else {
LOG("ss Found match of %d bytes at %d\n", match_length, match_pos);
hse->match_pos = match_pos;
hse->match_length = match_length;
ASSERT(match_pos < 1 << HEATSHRINK_ENCODER_WINDOW_BITS(hse) /*window_length*/);
return HSES_YIELD_TAG_BIT;
}
}
static void do_indexing(heatshrink_encoder *hse) {
#if HEATSHRINK_USE_INDEX
/* Build an index array I that contains flattened linked lists
* for the previous instances of every byte in the buffer.
*
* For example, if buf[200] == 'x', then index[200] will either
* be an offset i such that buf[i] == 'x', or a negative offset
* to indicate end-of-list. This significantly speeds up matching,
* while only using sizeof(uint16_t)*sizeof(buffer) bytes of RAM.
*
* Future optimization options:
* 1. Since any negative value represents end-of-list, the other
* 15 bits could be used to improve the index dynamically.
*
* 2. Likewise, the last lookahead_sz bytes of the index will
* not be usable, so temporary data could be stored there to
* dynamically improve the index.
* */
struct hs_index *hsi = HEATSHRINK_ENCODER_INDEX(hse);
int16_t last[256];
memset(last, 0xFF, sizeof(last));
uint8_t * const data = hse->buffer;
int16_t * const index = hsi->index;
const uint16_t input_offset = get_input_offset(hse);
const uint16_t end = input_offset + hse->input_size;
for (uint16_t i=0; i<end; i++) {
uint8_t v = data[i];
int16_t lv = last[v];
index[i] = lv;
last[v] = i;
}
#else
(void)hse;
#endif
}
