heatshrink_encoder.c File Reference

#include <stdlib.h>
#include <string.h>
#include <stdbool.h>
#include "heatshrink_encoder.h"

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Data Structures
struct	output_info

Macros
#define	LOG(...)   /* no-op */
#define	ASSERT(X)   /* no-op */
#define	MATCH_NOT_FOUND   ((uint16_t)-1)

Enumerations
enum	HSE_state {   HSES_NOT_FULL, HSES_FILLED, HSES_SEARCH, HSES_YIELD_TAG_BIT,   HSES_YIELD_LITERAL, HSES_YIELD_BR_INDEX, HSES_YIELD_BR_LENGTH, HSES_SAVE_BACKLOG,   HSES_FLUSH_BITS, HSES_DONE }
enum	{   FLAG_IS_FINISHING = 0x01, FLAG_HAS_LITERAL = 0x02, FLAG_ON_FINAL_LITERAL = 0x04, FLAG_BACKLOG_IS_PARTIAL = 0x08,   FLAG_BACKLOG_IS_FILLED = 0x10 }

Functions
static uint16_t	get_input_offset (heatshrink_encoder *hse)
static uint16_t	get_input_buffer_size (heatshrink_encoder *hse)
static uint16_t	get_lookahead_size (heatshrink_encoder *hse)
static void	add_tag_bit (heatshrink_encoder *hse, output_info *oi, uint8_t tag)
static int	can_take_byte (output_info *oi)
static int	is_finishing (heatshrink_encoder *hse)
static int	backlog_is_partial (heatshrink_encoder *hse)
static int	backlog_is_filled (heatshrink_encoder *hse)
static int	on_final_literal (heatshrink_encoder *hse)
static void	save_backlog (heatshrink_encoder *hse)
static int	has_literal (heatshrink_encoder *hse)
static void	push_bits (heatshrink_encoder *hse, uint8_t count, uint8_t bits, output_info *oi)
static uint8_t	push_outgoing_bits (heatshrink_encoder *hse, output_info *oi)
static void	push_literal_byte (heatshrink_encoder *hse, output_info *oi)
heatshrink_encoder *	heatshrink_encoder_alloc (uint8_t window_sz2, uint8_t lookahead_sz2)
void	heatshrink_encoder_free (heatshrink_encoder *hse)
void	heatshrink_encoder_reset (heatshrink_encoder *hse)
HSE_sink_res	heatshrink_encoder_sink (heatshrink_encoder *hse, uint8_t *in_buf, size_t size, size_t *input_size)
static uint16_t	find_longest_match (heatshrink_encoder *hse, uint16_t start, uint16_t end, const uint16_t maxlen, uint16_t *match_length)
static void	do_indexing (heatshrink_encoder *hse)
static HSE_state	st_step_search (heatshrink_encoder *hse)
static HSE_state	st_yield_tag_bit (heatshrink_encoder *hse, output_info *oi)
static HSE_state	st_yield_literal (heatshrink_encoder *hse, output_info *oi)
static HSE_state	st_yield_br_index (heatshrink_encoder *hse, output_info *oi)
static HSE_state	st_yield_br_length (heatshrink_encoder *hse, output_info *oi)
static HSE_state	st_save_backlog (heatshrink_encoder *hse)
static HSE_state	st_flush_bit_buffer (heatshrink_encoder *hse, output_info *oi)
HSE_poll_res	heatshrink_encoder_poll (heatshrink_encoder *hse, uint8_t *out_buf, size_t out_buf_size, size_t *output_size)
HSE_finish_res	heatshrink_encoder_finish (heatshrink_encoder *hse)

Macro Definition Documentation

ASSERT

#define ASSERT

(

X

)

/* no-op */

Definition at line 39 of file heatshrink_encoder.c.

Referenced by push_bits(), and st_step_search().

LOG

#define LOG

(

...

)

/* no-op */

Definition at line 38 of file heatshrink_encoder.c.

Referenced by add_tag_bit(), find_longest_match(), heatshrink_encoder_alloc(), heatshrink_encoder_finish(), heatshrink_encoder_poll(), heatshrink_encoder_sink(), push_bits(), push_literal_byte(), push_outgoing_bits(), st_flush_bit_buffer(), st_save_backlog(), st_step_search(), st_yield_br_index(), and st_yield_br_length().

MATCH_NOT_FOUND

#define MATCH_NOT_FOUND   ((uint16_t)-1)

Definition at line 57 of file heatshrink_encoder.c.

Referenced by find_longest_match(), and st_step_search().

Enumeration Type Documentation

anonymous enum

anonymous enum

Enumerator
FLAG_IS_FINISHING
FLAG_HAS_LITERAL
FLAG_ON_FINAL_LITERAL
FLAG_BACKLOG_IS_PARTIAL
FLAG_BACKLOG_IS_FILLED

Definition at line 43 of file heatshrink_encoder.c.

     {
    FLAG_IS_FINISHING = 0x01,
    FLAG_HAS_LITERAL = 0x02,
    FLAG_ON_FINAL_LITERAL = 0x04,
    FLAG_BACKLOG_IS_PARTIAL = 0x08,
    FLAG_BACKLOG_IS_FILLED = 0x10,
};

HSE_state

enum HSE_state

Enumerator
HSES_NOT_FULL
HSES_FILLED
HSES_SEARCH
HSES_YIELD_TAG_BIT
HSES_YIELD_LITERAL
HSES_YIELD_BR_INDEX
HSES_YIELD_BR_LENGTH
HSES_SAVE_BACKLOG
HSES_FLUSH_BITS
HSES_DONE

Definition at line 6 of file heatshrink_encoder.c.

             {
    HSES_NOT_FULL,              /* input buffer not full enough */
    HSES_FILLED,                /* buffer is full */
    HSES_SEARCH,                /* searching for patterns */
    HSES_YIELD_TAG_BIT,         /* yield tag bit */
    HSES_YIELD_LITERAL,         /* emit literal byte */
    HSES_YIELD_BR_INDEX,        /* yielding backref index */
    HSES_YIELD_BR_LENGTH,       /* yielding backref length */
    HSES_SAVE_BACKLOG,          /* copying buffer to backlog */
    HSES_FLUSH_BITS,            /* flush bit buffer */
    HSES_DONE,                  /* done */
} HSE_state;

Function Documentation

add_tag_bit()

static void add_tag_bit ( heatshrink_encoder *  hse, output_info *  oi, uint8_t  tag  )

static

Definition at line 413 of file heatshrink_encoder.c.

References LOG, and push_bits().

Referenced by st_yield_tag_bit().

                                                                               {
    LOG("-- adding tag bit: %d\n", tag);
    push_bits(hse, 1, tag, oi);
}

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backlog_is_filled()

static int backlog_is_filled ( heatshrink_encoder *  hse )

static

Definition at line 479 of file heatshrink_encoder.c.

References FLAG_BACKLOG_IS_FILLED, and heatshrink_encoder::flags.

Referenced by st_step_search().

                                                      {
    return hse->flags & FLAG_BACKLOG_IS_FILLED;
}

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backlog_is_partial()

static int backlog_is_partial ( heatshrink_encoder *  hse )

static

Definition at line 475 of file heatshrink_encoder.c.

References FLAG_BACKLOG_IS_PARTIAL, and heatshrink_encoder::flags.

Referenced by save_backlog(), and st_step_search().

                                                       {
    return hse->flags & FLAG_BACKLOG_IS_PARTIAL;
}

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can_take_byte()

static int can_take_byte ( output_info *  oi )

static

Definition at line 491 of file heatshrink_encoder.c.

References output_info::buf_size, and output_info::output_size.

Referenced by st_flush_bit_buffer(), st_yield_br_index(), st_yield_br_length(), st_yield_literal(), and st_yield_tag_bit().

                                          {
    return *oi->output_size < oi->buf_size;
}

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do_indexing()

static void do_indexing ( heatshrink_encoder *  hse )

static

Definition at line 432 of file heatshrink_encoder.c.

References heatshrink_encoder::buffer, get_input_offset(), HEATSHRINK_ENCODER_INDEX, hs_index::index, heatshrink_encoder::input_size, and memset.

Referenced by heatshrink_encoder_poll(), and heatshrink_encoder_sink().

                                                 {
#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);
    uint16_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];
        uint16_t lv = last[v];
        index[i] = lv;
        last[v] = i;
    }
#else
    (void)hse;
#endif
}

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find_longest_match()

static uint16_t find_longest_match ( heatshrink_encoder *  hse, uint16_t  start, uint16_t  end, const uint16_t  maxlen, uint16_t *  match_length  )

static

Definition at line 497 of file heatshrink_encoder.c.

References heatshrink_encoder::buffer, HEATSHRINK_ENCODER_INDEX, hs_index::index, LOG, and MATCH_NOT_FOUND.

Referenced by heatshrink_encoder_sink(), and st_step_search().

                                                                     {
    LOG("-- scanning for match of buf[%u:%u] between buf[%u:%u] (max %u bytes)\n",
        end, end + maxlen, start, end + maxlen - 1, maxlen);
    uint8_t *buf = hse->buffer;

    uint16_t match_maxlen = 0;
    uint16_t match_index = MATCH_NOT_FOUND;
    const uint16_t break_even_point = 3;
    uint16_t len = 0;
    uint8_t * const needlepoint = &buf[end];
#if HEATSHRINK_USE_INDEX
    struct hs_index *hsi = HEATSHRINK_ENCODER_INDEX(hse);
    int16_t pos = hsi->index[end];

    while (pos >= start) {
        uint8_t * const pospoint = &buf[pos];
        len = 0;

        /* Only check matches that will potentially beat the current maxlen.
         * This is redundant with the index if match_maxlen is 0, but the
         * added branch overhead to check if it == 0 seems to be worse. */
        if (pospoint[match_maxlen] != needlepoint[match_maxlen]) {
            pos = hsi->index[pos];
            continue;
        }

        for (len = 1; len < maxlen; len++) {
            if (pospoint[len] != needlepoint[len]) break;
        }

        if (len > match_maxlen) {
            match_maxlen = len;
            match_index = pos;
            if (len == maxlen) { break; } /* won't find better */
        }
        pos = hsi->index[pos];
    }
#else    
    for (int16_t pos=end - 1; pos >= start; pos--) {
        uint8_t * const pospoint = &buf[pos];
        if ((pospoint[match_maxlen] == needlepoint[match_maxlen])
            && (*pospoint == *needlepoint)) {
            for (len=1; len<maxlen; len++) {
                if (0) {
                    LOG("  --> cmp buf[%d] == 0x%02x against %02x (start %u)\n",
                        pos + len, pospoint[len], needlepoint[len], start);
                }
                if (pospoint[len] != needlepoint[len]) { break; }
            }
            if (len > match_maxlen) {
                match_maxlen = len;
                match_index = pos;
                if (len == maxlen) { break; } /* don't keep searching */
            }
        }
    }
#endif
    
    if (match_maxlen >= break_even_point) {
        LOG("-- best match: %u bytes at -%u\n",
            match_maxlen, end - match_index);
        *match_length = match_maxlen;
        return end - match_index;
    }
    LOG("-- none found\n");
    return MATCH_NOT_FOUND;
}

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get_input_buffer_size()

static uint16_t get_input_buffer_size ( heatshrink_encoder *  hse )

static

Definition at line 422 of file heatshrink_encoder.c.

References HEATSHRINK_ENCODER_WINDOW_BITS.

Referenced by get_input_offset(), heatshrink_encoder_alloc(), heatshrink_encoder_sink(), save_backlog(), and st_step_search().

                                                               {
    return (1 << HEATSHRINK_ENCODER_WINDOW_BITS(hse));
    (void)hse;
}

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get_input_offset()

static uint16_t get_input_offset ( heatshrink_encoder *  hse )

static

Definition at line 418 of file heatshrink_encoder.c.

References get_input_buffer_size().

Referenced by do_indexing(), heatshrink_encoder_sink(), push_literal_byte(), and st_step_search().

                                                          {
    return get_input_buffer_size(hse);
}

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get_lookahead_size()

static uint16_t get_lookahead_size ( heatshrink_encoder *  hse )

static

Definition at line 427 of file heatshrink_encoder.c.

References HEATSHRINK_ENCODER_LOOKAHEAD_BITS.

Referenced by st_step_search().

                                                            {
    return (1 << HEATSHRINK_ENCODER_LOOKAHEAD_BITS(hse));
    (void)hse;
}

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has_literal()

static int has_literal ( heatshrink_encoder *  hse )

static

Definition at line 487 of file heatshrink_encoder.c.

References FLAG_HAS_LITERAL, and heatshrink_encoder::flags.

Referenced by st_save_backlog().

                                                {
    return (hse->flags & FLAG_HAS_LITERAL);
}

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heatshrink_encoder_alloc()

heatshrink_encoder* heatshrink_encoder_alloc	(	uint8_t	window_sz2,
		uint8_t	lookahead_sz2
	)

Definition at line 78 of file heatshrink_encoder.c.

References get_input_buffer_size(), heatshrink_encoder_reset(), HEATSHRINK_FREE, HEATSHRINK_MALLOC, HEATSHRINK_MAX_WINDOW_BITS, HEATSHRINK_MIN_LOOKAHEAD_BITS, HEATSHRINK_MIN_WINDOW_BITS, hse, LOG, heatshrink_encoder::lookahead_sz2, NULL, heatshrink_encoder::search_index, hs_index::size, and heatshrink_encoder::window_sz2.

Referenced by compress_and_expand_and_check(), data_with_simple_repetition_should_match_with_absurdly_tiny_buffers(), data_without_duplication_should_match_with_absurdly_tiny_buffers(), encode(), encoder_alloc_should_reject_invalid_arguments(), encoder_poll_should_detect_repeated_substring(), encoder_poll_should_detect_repeated_substring_and_preserve_trailing_literal(), encoder_poll_should_indicate_when_no_input_is_provided(), encoder_poll_should_reject_nulls(), encoder_should_emit_data_without_repetitions_as_literal_sequence(), encoder_should_emit_series_of_same_byte_as_literal_then_backref(), encoder_sink_should_accept_input_when_it_will_fit(), encoder_sink_should_accept_partial_input_when_some_will_fit(), encoder_sink_should_reject_nulls(), and gen().

                               {
    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;
}

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heatshrink_encoder_finish()

HSE_finish_res heatshrink_encoder_finish

(

heatshrink_encoder *

hse

)

Definition at line 260 of file heatshrink_encoder.c.

References FLAG_IS_FINISHING, heatshrink_encoder::flags, HSER_FINISH_DONE, HSER_FINISH_ERROR_NULL, HSER_FINISH_MORE, HSES_DONE, HSES_FILLED, HSES_NOT_FULL, LOG, NULL, and heatshrink_encoder::state.

Referenced by compress_and_expand_and_check(), data_with_simple_repetition_should_match_with_absurdly_tiny_buffers(), data_without_duplication_should_match_with_absurdly_tiny_buffers(), encoder_finish_should_reject_nulls(), encoder_poll_should_detect_repeated_substring(), encoder_poll_should_detect_repeated_substring_and_preserve_trailing_literal(), encoder_should_emit_data_without_repetitions_as_literal_sequence(), encoder_should_emit_series_of_same_byte_as_literal_then_backref(), encoder_sink_read(), and gen().

                                                                  {
    if (hse == NULL) { return HSER_FINISH_ERROR_NULL; }
    LOG("-- setting is_finishing flag\n");
    hse->flags |= FLAG_IS_FINISHING;
    if (hse->state == HSES_NOT_FULL) { hse->state = HSES_FILLED; }
    return hse->state == HSES_DONE ? HSER_FINISH_DONE : HSER_FINISH_MORE;
}

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heatshrink_encoder_free()

void heatshrink_encoder_free

(

heatshrink_encoder *

hse

)

Definition at line 114 of file heatshrink_encoder.c.

References HEATSHRINK_ENCODER_WINDOW_BITS, and HEATSHRINK_FREE.

Referenced by compress_and_expand_and_check(), data_with_simple_repetition_should_match_with_absurdly_tiny_buffers(), data_without_duplication_should_match_with_absurdly_tiny_buffers(), encode(), encoder_poll_should_detect_repeated_substring(), encoder_poll_should_detect_repeated_substring_and_preserve_trailing_literal(), encoder_poll_should_indicate_when_no_input_is_provided(), encoder_poll_should_reject_nulls(), encoder_should_emit_data_without_repetitions_as_literal_sequence(), encoder_should_emit_series_of_same_byte_as_literal_then_backref(), encoder_sink_should_accept_input_when_it_will_fit(), encoder_sink_should_accept_partial_input_when_some_will_fit(), encoder_sink_should_reject_nulls(), and gen().

                                                      {
    size_t buf_sz = (2 << HEATSHRINK_ENCODER_WINDOW_BITS(hse));
#if HEATSHRINK_USE_INDEX
    size_t index_sz = sizeof(struct hs_index) + hse->search_index->size;
    HEATSHRINK_FREE(hse->search_index, index_sz);
    (void)index_sz;
#endif
    HEATSHRINK_FREE(hse, sizeof(heatshrink_encoder) + buf_sz);
    (void)buf_sz;
}

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heatshrink_encoder_poll()

HSE_poll_res heatshrink_encoder_poll	(	heatshrink_encoder *	hse,
		uint8_t *	out_buf,
		size_t	out_buf_size,
		size_t *	output_size
	)

Definition at line 198 of file heatshrink_encoder.c.

References output_info::buf, output_info::buf_size, do_indexing(), heatshrink_encoder::flags, HSER_POLL_EMPTY, HSER_POLL_ERROR_MISUSE, HSER_POLL_ERROR_NULL, HSER_POLL_MORE, HSES_DONE, HSES_FILLED, HSES_FLUSH_BITS, HSES_NOT_FULL, HSES_SAVE_BACKLOG, HSES_SEARCH, HSES_YIELD_BR_INDEX, HSES_YIELD_BR_LENGTH, HSES_YIELD_LITERAL, HSES_YIELD_TAG_BIT, LOG, NULL, output_info::output_size, st_flush_bit_buffer(), st_save_backlog(), st_step_search(), st_yield_br_index(), st_yield_br_length(), st_yield_literal(), st_yield_tag_bit(), and heatshrink_encoder::state.

Referenced by compress_and_expand_and_check(), data_with_simple_repetition_should_match_with_absurdly_tiny_buffers(), data_without_duplication_should_match_with_absurdly_tiny_buffers(), encoder_poll_should_detect_repeated_substring(), encoder_poll_should_detect_repeated_substring_and_preserve_trailing_literal(), encoder_poll_should_indicate_when_no_input_is_provided(), encoder_poll_should_reject_nulls(), encoder_should_emit_data_without_repetitions_as_literal_sequence(), encoder_should_emit_series_of_same_byte_as_literal_then_backref(), encoder_sink_read(), and gen().

                                                                    {
    if ((hse == NULL) || (out_buf == NULL) || (output_size == NULL)) {
        return HSER_POLL_ERROR_NULL;
    }
    if (out_buf_size == 0) {
        LOG("-- MISUSE: output buffer size is 0\n");
        return HSER_POLL_ERROR_MISUSE;
    }
    *output_size = 0;

    output_info oi;
    oi.buf = out_buf;
    oi.buf_size = out_buf_size;
    oi.output_size = output_size;

    while (1) {
        LOG("-- polling, state %u (%s), flags 0x%02x\n",
            hse->state, state_names[hse->state], hse->flags);

        uint8_t in_state = hse->state;
        switch (in_state) {
        case HSES_NOT_FULL:
            return HSER_POLL_EMPTY;
        case HSES_FILLED:
            do_indexing(hse);
            hse->state = HSES_SEARCH;
            break;
        case HSES_SEARCH:
            hse->state = st_step_search(hse);
            break;
        case HSES_YIELD_TAG_BIT:
            hse->state = st_yield_tag_bit(hse, &oi);
            break;
        case HSES_YIELD_LITERAL:
            hse->state = st_yield_literal(hse, &oi);
            break;
        case HSES_YIELD_BR_INDEX:
            hse->state = st_yield_br_index(hse, &oi);
            break;
        case HSES_YIELD_BR_LENGTH:
            hse->state = st_yield_br_length(hse, &oi);
            break;
        case HSES_SAVE_BACKLOG:
            hse->state = st_save_backlog(hse);
            break;
        case HSES_FLUSH_BITS:
            hse->state = st_flush_bit_buffer(hse, &oi);
        case HSES_DONE:
            return HSER_POLL_EMPTY;
        default:
            LOG("-- bad state %s\n", state_names[hse->state]);
            return HSER_POLL_ERROR_MISUSE;
        }

        if (hse->state == in_state) {
            /* Check if output buffer is exhausted. */
            if (*output_size == out_buf_size) return HSER_POLL_MORE;
        }
    }
}

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heatshrink_encoder_reset()

void heatshrink_encoder_reset

(

heatshrink_encoder *

hse

)

Definition at line 126 of file heatshrink_encoder.c.

References heatshrink_encoder::bit_index, heatshrink_encoder::buffer, heatshrink_encoder::current_byte, heatshrink_encoder::flags, HEATSHRINK_ENCODER_WINDOW_BITS, HSES_NOT_FULL, heatshrink_encoder::input_size, heatshrink_encoder::match_length, heatshrink_encoder::match_scan_index, memset, heatshrink_encoder::outgoing_bits, heatshrink_encoder::outgoing_bits_count, and heatshrink_encoder::state.

Referenced by compress_and_expand_and_check(), and heatshrink_encoder_alloc().

                                                       {
    size_t buf_sz = (2 << HEATSHRINK_ENCODER_WINDOW_BITS(hse));
    memset(hse->buffer, 0, buf_sz);
    hse->input_size = 0;
    hse->state = HSES_NOT_FULL;
    hse->match_scan_index = 0;
    hse->flags = 0;
    hse->bit_index = 0x80;
    hse->current_byte = 0x00;
    hse->match_length = 0;

    hse->outgoing_bits = 0x0000;
    hse->outgoing_bits_count = 0;

    #ifdef LOOP_DETECT
    hse->loop_detect = (uint32_t)-1;
    #endif
}

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heatshrink_encoder_sink()

HSE_sink_res heatshrink_encoder_sink	(	heatshrink_encoder *	hse,
		uint8_t *	in_buf,
		size_t	size,
		size_t *	input_size
	)

Definition at line 145 of file heatshrink_encoder.c.

References heatshrink_encoder::buffer, do_indexing(), find_longest_match(), get_input_buffer_size(), get_input_offset(), hse, HSER_SINK_ERROR_MISUSE, HSER_SINK_ERROR_NULL, HSER_SINK_OK, HSES_FILLED, HSES_NOT_FULL, heatshrink_encoder::input_size, is_finishing(), LOG, memcpy, NULL, hs_index::size, st_flush_bit_buffer(), st_save_backlog(), st_step_search(), st_yield_br_index(), st_yield_br_length(), st_yield_literal(), st_yield_tag_bit(), and heatshrink_encoder::state.

Referenced by compress_and_expand_and_check(), data_with_simple_repetition_should_match_with_absurdly_tiny_buffers(), data_without_duplication_should_match_with_absurdly_tiny_buffers(), encoder_poll_should_detect_repeated_substring(), encoder_poll_should_detect_repeated_substring_and_preserve_trailing_literal(), encoder_should_emit_data_without_repetitions_as_literal_sequence(), encoder_should_emit_series_of_same_byte_as_literal_then_backref(), encoder_sink_read(), encoder_sink_should_accept_input_when_it_will_fit(), encoder_sink_should_accept_partial_input_when_some_will_fit(), encoder_sink_should_reject_nulls(), and gen().

                                                          {
    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;
}

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is_finishing()

static int is_finishing ( heatshrink_encoder *  hse )

static

Definition at line 471 of file heatshrink_encoder.c.

References FLAG_IS_FINISHING, and heatshrink_encoder::flags.

Referenced by heatshrink_encoder_sink(), st_save_backlog(), and st_step_search().

                                                 {
    return hse->flags & FLAG_IS_FINISHING;
}

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on_final_literal()

static int on_final_literal ( heatshrink_encoder *  hse )

static

Definition at line 483 of file heatshrink_encoder.c.

References FLAG_ON_FINAL_LITERAL, and heatshrink_encoder::flags.

Referenced by st_yield_literal().

                                                     {
    return hse->flags & FLAG_ON_FINAL_LITERAL;
}

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push_bits()

static void push_bits ( heatshrink_encoder *  hse, uint8_t  count, uint8_t  bits, output_info *  oi  )

static

Definition at line 587 of file heatshrink_encoder.c.

References ASSERT, heatshrink_encoder::bit_index, output_info::buf, heatshrink_encoder::current_byte, LOG, and output_info::output_size.

Referenced by add_tag_bit(), push_literal_byte(), and push_outgoing_bits().

                         {
    ASSERT(count <= 8);
    LOG("++ push_bits: %d bits, input of 0x%02x\n", count, bits);

    /* If adding a whole byte and at the start of a new output byte,
     * just push it through whole and skip the bit IO loop. */
    if (count == 8 && hse->bit_index == 0x80) {
        oi->buf[(*oi->output_size)++] = bits;
    } else {
        for (int i=count - 1; i>=0; i--) {
            bool bit = bits & (1 << i);
            if (bit) { hse->current_byte |= hse->bit_index; }
            if (0) {
                LOG("  -- setting bit %d at bit index 0x%02x, byte => 0x%02x\n",
                    bit ? 1 : 0, hse->bit_index, hse->current_byte);
            }
            hse->bit_index >>= 1;
            if (hse->bit_index == 0x00) {
                hse->bit_index = 0x80;
                LOG(" > pushing byte 0x%02x\n", hse->current_byte);
                oi->buf[(*oi->output_size)++] = hse->current_byte;
                hse->current_byte = 0x00;
            }
        }
    }
}

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push_literal_byte()

static void push_literal_byte ( heatshrink_encoder *  hse, output_info *  oi  )

static

Definition at line 615 of file heatshrink_encoder.c.

References heatshrink_encoder::buffer, get_input_offset(), isprint, LOG, heatshrink_encoder::match_scan_index, and push_bits().

Referenced by st_yield_literal().

                                                                        {
    uint16_t processed_offset = hse->match_scan_index - 1;
    uint16_t input_offset = get_input_offset(hse) + processed_offset;
    uint8_t c = hse->buffer[input_offset];
    LOG("-- yielded literal byte 0x%02x ('%c') from +%d\n",
        c, isprint(c) ? c : '.', input_offset);
    push_bits(hse, 8, c, oi);
}

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push_outgoing_bits()

static uint8_t push_outgoing_bits ( heatshrink_encoder *  hse, output_info *  oi  )

static

Definition at line 566 of file heatshrink_encoder.c.

References LOG, heatshrink_encoder::outgoing_bits, heatshrink_encoder::outgoing_bits_count, and push_bits().

Referenced by st_yield_br_index(), and st_yield_br_length().

                                                                            {
    uint8_t count = 0;
    uint8_t bits = 0;
    if (hse->outgoing_bits_count > 8) {
        count = 8;
        bits = hse->outgoing_bits >> (hse->outgoing_bits_count - 8);
    } else {
        count = hse->outgoing_bits_count;
        bits = hse->outgoing_bits;
    }

    if (count > 0) {
        LOG("-- pushing %d outgoing bits: 0x%02x\n", count, bits);
        push_bits(hse, count, bits, oi);
        hse->outgoing_bits_count -= count;
    }
    return count;
}

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save_backlog()

static void save_backlog ( heatshrink_encoder *  hse )

static

Definition at line 624 of file heatshrink_encoder.c.

References backlog_is_partial(), heatshrink_encoder::buffer, FLAG_BACKLOG_IS_FILLED, FLAG_BACKLOG_IS_PARTIAL, heatshrink_encoder::flags, get_input_buffer_size(), heatshrink_encoder::input_size, and heatshrink_encoder::match_scan_index.

Referenced by st_save_backlog().

                                                  {
    size_t input_buf_sz = get_input_buffer_size(hse);
    
    uint16_t msi = hse->match_scan_index;
    
    /* Copy processed data to beginning of buffer, so it can be
     * used for future matches. Don't bother checking whether the
     * input is less than the maximum size, because if it isn't,
     * we're done anyway. */
    uint16_t rem = input_buf_sz - msi; // unprocessed bytes
    uint16_t shift_sz = input_buf_sz + rem;

    memmove(&hse->buffer[0],
        &hse->buffer[input_buf_sz - rem],
        shift_sz);
        
    if (backlog_is_partial(hse)) {
        /* The whole backlog is filled in now, so include it in scans. */
        hse->flags |= FLAG_BACKLOG_IS_FILLED;
    } else {
        /* Include backlog, except for the first lookahead_sz bytes, which
         * are still undefined. */
        hse->flags |= FLAG_BACKLOG_IS_PARTIAL;
    }
    hse->match_scan_index = 0;
    hse->input_size -= input_buf_sz - rem;
}

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st_flush_bit_buffer()

static HSE_state st_flush_bit_buffer ( heatshrink_encoder *  hse, output_info *  oi  )

static

Definition at line 398 of file heatshrink_encoder.c.

References heatshrink_encoder::bit_index, output_info::buf, can_take_byte(), heatshrink_encoder::current_byte, HSES_DONE, HSES_FLUSH_BITS, LOG, and output_info::output_size.

Referenced by heatshrink_encoder_poll(), and heatshrink_encoder_sink().

                         {
    if (hse->bit_index == 0x80) {
        LOG("-- done!\n");
        return HSES_DONE;
    } else if (can_take_byte(oi)) {
        LOG("-- flushing remaining byte (bit_index == 0x%02x)\n", hse->bit_index);
        oi->buf[(*oi->output_size)++] = hse->current_byte;
        LOG("-- done!\n");
        return HSES_DONE;
    } else {
        return HSES_FLUSH_BITS;
    }
}

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st_save_backlog()

static HSE_state st_save_backlog ( heatshrink_encoder *  hse )

static

Definition at line 382 of file heatshrink_encoder.c.

References FLAG_ON_FINAL_LITERAL, heatshrink_encoder::flags, has_literal(), HSES_FLUSH_BITS, HSES_NOT_FULL, HSES_YIELD_TAG_BIT, is_finishing(), LOG, and save_backlog().

Referenced by heatshrink_encoder_poll(), and heatshrink_encoder_sink().

                                                          {
    if (is_finishing(hse)) {
        /* copy remaining literal (if necessary) */
        if (has_literal(hse)) {
            hse->flags |= FLAG_ON_FINAL_LITERAL;
            return HSES_YIELD_TAG_BIT;
        } else {
            return HSES_FLUSH_BITS;
        }
    } else {
        LOG("-- saving backlog\n");
        save_backlog(hse);
        return HSES_NOT_FULL;
    }
}

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st_step_search()

static HSE_state st_step_search ( heatshrink_encoder *  hse )

static

Definition at line 268 of file heatshrink_encoder.c.

References ASSERT, backlog_is_filled(), backlog_is_partial(), find_longest_match(), FLAG_HAS_LITERAL, heatshrink_encoder::flags, get_input_buffer_size(), get_input_offset(), get_lookahead_size(), HSES_SAVE_BACKLOG, HSES_YIELD_TAG_BIT, heatshrink_encoder::input_size, is_finishing(), LOG, heatshrink_encoder::match_length, MATCH_NOT_FOUND, heatshrink_encoder::match_pos, heatshrink_encoder::match_scan_index, and heatshrink_encoder::window_sz2.

Referenced by heatshrink_encoder_poll(), and heatshrink_encoder_sink().

                                                         {
    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;
    }
}

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st_yield_br_index()

static HSE_state st_yield_br_index ( heatshrink_encoder *  hse, output_info *  oi  )

static

Definition at line 350 of file heatshrink_encoder.c.

References can_take_byte(), HEATSHRINK_ENCODER_LOOKAHEAD_BITS, HSES_YIELD_BR_INDEX, HSES_YIELD_BR_LENGTH, LOG, heatshrink_encoder::match_length, heatshrink_encoder::match_pos, heatshrink_encoder::outgoing_bits, heatshrink_encoder::outgoing_bits_count, and push_outgoing_bits().

Referenced by heatshrink_encoder_poll(), and heatshrink_encoder_sink().

                         {
    if (can_take_byte(oi)) {
        LOG("-- yielding backref index %u\n", hse->match_pos);
        if (push_outgoing_bits(hse, oi) > 0) {
            return HSES_YIELD_BR_INDEX; /* continue */
        } else {
            hse->outgoing_bits = hse->match_length - 1;
            hse->outgoing_bits_count = HEATSHRINK_ENCODER_LOOKAHEAD_BITS(hse);
            return HSES_YIELD_BR_LENGTH; /* done */
        }
    } else {
        return HSES_YIELD_BR_INDEX; /* continue */
    }
}

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st_yield_br_length()

static HSE_state st_yield_br_length ( heatshrink_encoder *  hse, output_info *  oi  )

static

Definition at line 366 of file heatshrink_encoder.c.

References can_take_byte(), HSES_SEARCH, HSES_YIELD_BR_LENGTH, LOG, heatshrink_encoder::match_length, heatshrink_encoder::match_scan_index, and push_outgoing_bits().

Referenced by heatshrink_encoder_poll(), and heatshrink_encoder_sink().

                         {
    if (can_take_byte(oi)) {
        LOG("-- yielding backref length %u\n", hse->match_length);
        if (push_outgoing_bits(hse, oi) > 0) {
            return HSES_YIELD_BR_LENGTH;
        } else {
            hse->match_scan_index += hse->match_length;
            hse->match_length = 0;
            return HSES_SEARCH;
        }
    } else {
        return HSES_YIELD_BR_LENGTH;
    }
}

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st_yield_literal()

static HSE_state st_yield_literal ( heatshrink_encoder *  hse, output_info *  oi  )

static

Definition at line 338 of file heatshrink_encoder.c.

References can_take_byte(), FLAG_HAS_LITERAL, heatshrink_encoder::flags, HSES_FLUSH_BITS, HSES_SEARCH, HSES_YIELD_LITERAL, HSES_YIELD_TAG_BIT, heatshrink_encoder::match_length, on_final_literal(), and push_literal_byte().

Referenced by heatshrink_encoder_poll(), and heatshrink_encoder_sink().

                         {
    if (can_take_byte(oi)) {
        push_literal_byte(hse, oi);
        hse->flags &= ~FLAG_HAS_LITERAL;
        if (on_final_literal(hse)) { return HSES_FLUSH_BITS; }
        return hse->match_length > 0 ? HSES_YIELD_TAG_BIT : HSES_SEARCH;
    } else {
        return HSES_YIELD_LITERAL;
    }
}

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st_yield_tag_bit()

static HSE_state st_yield_tag_bit ( heatshrink_encoder *  hse, output_info *  oi  )

static

Definition at line 321 of file heatshrink_encoder.c.

References add_tag_bit(), can_take_byte(), HEATSHRINK_BACKREF_MARKER, HEATSHRINK_ENCODER_WINDOW_BITS, HEATSHRINK_LITERAL_MARKER, HSES_YIELD_BR_INDEX, HSES_YIELD_LITERAL, HSES_YIELD_TAG_BIT, heatshrink_encoder::match_length, heatshrink_encoder::match_pos, heatshrink_encoder::outgoing_bits, and heatshrink_encoder::outgoing_bits_count.

Referenced by heatshrink_encoder_poll(), and heatshrink_encoder_sink().

                         {
    if (can_take_byte(oi)) {
        if (hse->match_length == 0) {
            add_tag_bit(hse, oi, HEATSHRINK_LITERAL_MARKER);
            return HSES_YIELD_LITERAL;
        } else {
            add_tag_bit(hse, oi, HEATSHRINK_BACKREF_MARKER);
            hse->outgoing_bits = hse->match_pos - 1;
            hse->outgoing_bits_count = HEATSHRINK_ENCODER_WINDOW_BITS(hse);
            return HSES_YIELD_BR_INDEX;
        }
    } else {
        return HSES_YIELD_TAG_BIT; /* output is full, continue */
    }
}

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