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Commit 86699925 authored by Vadim Vygonets's avatar Vadim Vygonets Committed by Scott Vokes
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Process tag bit sooner in decoder 

Fix the bug where last 7 bits are not processed.

Test case:
$ echo -n aaaa | ./heatshrink -w4 -l2 | ./heatshrink -dw4 -l2 | hexdump -C

expected output:
00000000  61 61 61 61                                       |aaaa|
00000004

bug:
00000000  61                                                |a|
00000001

Conflicts:
	heatshrink_decoder.c
parent 9bef9df5
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dec_sm.dot
+ 9
− 14
View file @ 86699925
digraph {
graph [label="Decoder state machine", labelloc="t"]
Start [style="invis", shape="point"]
empty
input_available
tag_bit
yield_literal
backref_index_msb
backref_index_lsb
backref_count_msb
backref_count_lsb
yield_backref
check_for_more_input
done [peripheries=2]
empty->input_available [label="sink()", color="blue", weight=10]
Start->empty
tag_bit->tag_bit [label="sink()", color="blue", weight=10]
Start->tag_bit
input_available->yield_literal [label="pop 1-bit"]
input_available->backref_index_msb [label="pop 0-bit", weight=10]
input_available->backref_index_lsb [label="pop 0-bit, index <8 bits", weight=10]
tag_bit->yield_literal [label="pop 1-bit"]
tag_bit->backref_index_msb [label="pop 0-bit", weight=10]
tag_bit->backref_index_lsb [label="pop 0-bit, index <8 bits", weight=10]
yield_literal->yield_literal [label="sink()", color="blue"]
yield_literal->yield_literal [label="poll()", color="red"]
yield_literal->check_for_more_input [label="poll(), done", color="red"]
yield_literal->tag_bit [label="poll(), done", color="red"]
backref_index_msb->backref_index_msb [label="sink()", color="blue"]
backref_index_msb->backref_index_lsb [label="pop index, upper bits", weight=10]
......@@ -42,11 +40,8 @@ digraph {
yield_backref->yield_backref [label="sink()", color="blue"]
yield_backref->yield_backref [label="poll()", color="red"]
yield_backref->check_for_more_input [label="poll(), done",
yield_backref->tag_bit [label="poll(), done",
color="red", weight=10]
check_for_more_input->empty [label="no"]
check_for_more_input->input_available [label="yes"]
empty->done [label="finish()", color="blue"]
tag_bit->done [label="finish()", color="blue"]
}
heatshrink_decoder.c
+ 15
− 31
View file @ 86699925
......@@ -4,15 +4,13 @@
/* States for the polling state machine. */
typedef enum {
HSDS_EMPTY, /* no input to process */
HSDS_INPUT_AVAILABLE, /* new input, completely unprocessed */
HSDS_TAG_BIT, /* tag bit */
HSDS_YIELD_LITERAL, /* ready to yield literal byte */
HSDS_BACKREF_INDEX_MSB, /* most significant byte of index */
HSDS_BACKREF_INDEX_LSB, /* least significant byte of index */
HSDS_BACKREF_COUNT_MSB, /* most significant byte of count */
HSDS_BACKREF_COUNT_LSB, /* least significant byte of count */
HSDS_YIELD_BACKREF, /* ready to yield back-reference */
HSDS_CHECK_FOR_MORE_INPUT, /* check if input is exhausted */
} HSD_state;
#if HEATSHRINK_DEBUGGING_LOGS
......@@ -22,15 +20,13 @@ typedef enum {
#define LOG(...) fprintf(stderr, __VA_ARGS__)
#define ASSERT(X) assert(X)
static const char *state_names[] = {
"empty",
"input_available",
"tag_bit",
"yield_literal",
"backref_index_msb",
"backref_index_lsb",
"backref_count_msb",
"backref_count_lsb",
"yield_backref",
"check_for_more_input",
};
#else
#define LOG(...) /* no-op */
......@@ -85,7 +81,7 @@ 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_EMPTY;
hsd->state = HSDS_TAG_BIT;
hsd->input_size = 0;
hsd->input_index = 0;
hsd->bit_index = 0x00;
......@@ -113,10 +109,6 @@ HSD_sink_res heatshrink_decoder_sink(heatshrink_decoder *hsd,
/* copy into input buffer (at head of buffers) */
memcpy(&hsd->buffers[hsd->input_size], in_buf, size);
hsd->input_size += size;
if (hsd->state == HSDS_EMPTY) {
hsd->state = HSDS_INPUT_AVAILABLE;
hsd->input_index = 0;
}
*input_size = size;
return HSDR_SINK_OK;
}
......@@ -130,7 +122,7 @@ HSD_sink_res heatshrink_decoder_sink(heatshrink_decoder *hsd,
#define BACKREF_INDEX_BITS(HSD) (HEATSHRINK_DECODER_WINDOW_BITS(HSD))
// States
static HSD_state st_input_available(heatshrink_decoder *hsd);
static HSD_state st_tag_bit(heatshrink_decoder *hsd);
static HSD_state st_yield_literal(heatshrink_decoder *hsd,
output_info *oi);
static HSD_state st_backref_index_msb(heatshrink_decoder *hsd);
......@@ -139,7 +131,6 @@ static HSD_state st_backref_count_msb(heatshrink_decoder *hsd);
static HSD_state st_backref_count_lsb(heatshrink_decoder *hsd);
static HSD_state st_yield_backref(heatshrink_decoder *hsd,
output_info *oi);
static HSD_state st_check_for_input(heatshrink_decoder *hsd);
HSD_poll_res heatshrink_decoder_poll(heatshrink_decoder *hsd,
uint8_t *out_buf, size_t out_buf_size, size_t *output_size) {
......@@ -158,10 +149,8 @@ HSD_poll_res heatshrink_decoder_poll(heatshrink_decoder *hsd,
hsd->state, state_names[hsd->state], hsd->input_size);
uint8_t in_state = hsd->state;
switch (in_state) {
case HSDS_EMPTY:
return HSDR_POLL_EMPTY;
case HSDS_INPUT_AVAILABLE:
hsd->state = st_input_available(hsd);
case HSDS_TAG_BIT:
hsd->state = st_tag_bit(hsd);
break;
case HSDS_YIELD_LITERAL:
hsd->state = st_yield_literal(hsd, &oi);
......@@ -181,9 +170,6 @@ HSD_poll_res heatshrink_decoder_poll(heatshrink_decoder *hsd,
case HSDS_YIELD_BACKREF:
hsd->state = st_yield_backref(hsd, &oi);
break;
case HSDS_CHECK_FOR_MORE_INPUT:
hsd->state = st_check_for_input(hsd);
break;
default:
return HSDR_POLL_ERROR_UNKNOWN;
}
......@@ -197,9 +183,11 @@ HSD_poll_res heatshrink_decoder_poll(heatshrink_decoder *hsd,
}
}
static HSD_state st_input_available(heatshrink_decoder *hsd) {
uint16_t bits = get_bits(hsd, 1); // get tag bit
if (bits) {
static HSD_state st_tag_bit(heatshrink_decoder *hsd) {
uint32_t bits = get_bits(hsd, 1); // get tag bit
if (bits == NO_BITS) {
return HSDS_TAG_BIT;
} else if (bits) {
return HSDS_YIELD_LITERAL;
} else if (HEATSHRINK_DECODER_WINDOW_BITS(hsd) > 8) {
return HSDS_BACKREF_INDEX_MSB;
......@@ -223,7 +211,7 @@ static HSD_state st_yield_literal(heatshrink_decoder *hsd,
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;
return HSDS_TAG_BIT;
} else {
return HSDS_YIELD_LITERAL;
}
......@@ -292,15 +280,11 @@ static HSD_state st_yield_backref(heatshrink_decoder *hsd,
LOG(" -- ++ 0x%02x\n", c);
}
hsd->output_count -= count;
if (hsd->output_count == 0) { return HSDS_CHECK_FOR_MORE_INPUT; }
if (hsd->output_count == 0) { return HSDS_TAG_BIT; }
}
return HSDS_YIELD_BACKREF;
}
static HSD_state st_check_for_input(heatshrink_decoder *hsd) {
return (hsd->input_size == 0) ? HSDS_EMPTY : HSDS_INPUT_AVAILABLE;
}
/* Get the next COUNT bits from the input buffer, saving incremental progress.
* Returns NO_BITS on end of input, or if more than 15 bits are requested. */
static uint16_t get_bits(heatshrink_decoder *hsd, uint8_t count) {
......@@ -353,8 +337,8 @@ static uint16_t get_bits(heatshrink_decoder *hsd, uint8_t count) {
HSD_finish_res heatshrink_decoder_finish(heatshrink_decoder *hsd) {
if (hsd == NULL) { return HSDR_FINISH_ERROR_NULL; }
switch (hsd->state) {
case HSDS_EMPTY:
return HSDR_FINISH_DONE;
case HSDS_TAG_BIT:
return hsd->input_size == 0 ? HSDR_FINISH_DONE : HSDR_FINISH_MORE;
/* If we want to finish with no input, but are in these states, it's
* because the 0-bit padding to the last byte looks like a backref
......
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