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-rw-r--r--lisiblepng/meson.build4
-rw-r--r--lisiblepng/src/lisiblepng/bitstream.c42
-rw-r--r--lisiblepng/src/lisiblepng/bitstream.h4
-rw-r--r--lisiblepng/src/lisiblepng/deflate.c24
4 files changed, 39 insertions, 35 deletions
diff --git a/lisiblepng/meson.build b/lisiblepng/meson.build
index 22510fe..ae70175 100644
--- a/lisiblepng/meson.build
+++ b/lisiblepng/meson.build
@@ -1,6 +1,10 @@
cc = meson.get_compiler('c')
m_dep = cc.find_library('m', required: true)
+if get_option('buildtype').startswith('debug')
+ add_project_arguments('-DLPNG_DEBUG_LOG', language: ['c'])
+endif
+
lisiblepng_incdir = include_directories('src/')
lisiblepng_lib = library('lisiblepng', 'src/lisiblepng.c', 'src/lisiblepng/deflate.c', 'src/lisiblepng/bitstream.c', dependencies: [m_dep])
lisiblepng_dep = declare_dependency(include_directories: lisiblepng_incdir, link_with: [lisiblepng_lib], dependencies: [m_dep])
diff --git a/lisiblepng/src/lisiblepng/bitstream.c b/lisiblepng/src/lisiblepng/bitstream.c
index e7ddb79..83e70c6 100644
--- a/lisiblepng/src/lisiblepng/bitstream.c
+++ b/lisiblepng/src/lisiblepng/bitstream.c
@@ -10,44 +10,40 @@ void Bitstream_init(Bitstream *bitstream, const uint8_t *data,
ASSERT(data != NULL);
bitstream->data = data;
bitstream->data_size = data_size;
- bitstream->current_byte_index = 0;
- bitstream->current_bit_offset = 0;
+ bitstream->byte_offset = 0;
+ bitstream->bit_index = 0;
}
void bitstream_advance(Bitstream *bitstream, size_t bit_count) {
ASSERT(bitstream != NULL);
- uint8_t current_bit = bitstream->current_bit_offset;
- bitstream->current_byte_index =
- bitstream->current_byte_index + (current_bit + bit_count) / 8;
- bitstream->current_bit_offset = (current_bit + bit_count) % 8;
+ uint8_t current_bit = bitstream->bit_index;
+ bitstream->byte_offset =
+ bitstream->byte_offset + (current_bit + bit_count) / 8;
+ bitstream->bit_index = (current_bit + bit_count) % 8;
}
void Bitstream_skip(Bitstream *bitstream, size_t bit_count) {
ASSERT(bitstream != NULL);
bitstream_advance(bitstream, bit_count);
}
-
uint16_t Bitstream_next_bits(Bitstream *bitstream, int bit_count) {
ASSERT(bitstream != NULL);
ASSERT(bit_count <= 16);
- ASSERT((bitstream->current_bit_offset + (size_t)bit_count) / 8 <=
+ ASSERT((bitstream->bit_index + bit_count - 1) / 8 + bitstream->byte_offset <
bitstream->data_size);
- int bit_to_read = bit_count;
- uint16_t val = bitstream->data[bitstream->current_byte_index] >>
- bitstream->current_bit_offset;
-
- size_t bit_read = MIN(bit_count, 8 - bitstream->current_bit_offset);
- bitstream_advance(bitstream, bit_read);
- bit_to_read -= bit_read;
- while (bit_to_read > 0) {
- val |= (bitstream->data[bitstream->current_byte_index] >>
- bitstream->current_bit_offset)
- << bit_read;
- bit_read = MIN(bit_to_read, 8 - bitstream->current_bit_offset);
- bitstream_advance(bitstream, bit_read);
- bit_to_read -= bit_read;
+ uint16_t val = 0;
+ int bits_collected = 0;
+ while (bits_collected < bit_count) {
+ int bits_in_current_byte = 8 - bitstream->bit_index;
+ int bits_to_extract = MIN(bit_count - bits_collected, bits_in_current_byte);
+ uint16_t extracted_bits =
+ (bitstream->data[bitstream->byte_offset] >> bitstream->bit_index) &
+ ((1 << bits_to_extract) - 1);
+ val |= extracted_bits << bits_collected;
+ bits_collected += bits_to_extract;
+ bitstream_advance(bitstream, bits_to_extract);
}
- return (val & ((1 << bit_count) - 1));
+ return val;
}
diff --git a/lisiblepng/src/lisiblepng/bitstream.h b/lisiblepng/src/lisiblepng/bitstream.h
index 72d8295..2cb4fdc 100644
--- a/lisiblepng/src/lisiblepng/bitstream.h
+++ b/lisiblepng/src/lisiblepng/bitstream.h
@@ -8,8 +8,8 @@ typedef struct {
const uint8_t *data;
size_t data_size;
- size_t current_byte_index;
- uint8_t current_bit_offset;
+ size_t byte_offset;
+ uint8_t bit_index;
} Bitstream;
void Bitstream_init(Bitstream *bitstream, const uint8_t *data,
diff --git a/lisiblepng/src/lisiblepng/deflate.c b/lisiblepng/src/lisiblepng/deflate.c
index 5b33b1d..36073c6 100644
--- a/lisiblepng/src/lisiblepng/deflate.c
+++ b/lisiblepng/src/lisiblepng/deflate.c
@@ -71,7 +71,7 @@ void OutputBuffer_expand(OutputBuffer *output_buffer) {
output_buffer->cap = new_cap;
}
-void OutputBuffer_push(OutputBuffer *output_buffer, char byte) {
+void OutputBuffer_push(OutputBuffer *output_buffer, uint8_t byte) {
ASSERT(output_buffer != NULL);
if (output_buffer->len == output_buffer->cap) {
OutputBuffer_expand(output_buffer);
@@ -196,9 +196,13 @@ bool deflate_decompress_(Bitstream *bitstream,
return false;
}
if (symbol < 256) {
- OutputBuffer_push(output, (char)symbol);
+ OutputBuffer_push(output, symbol);
} else if (symbol > 256) {
symbol -= 257;
+ if (symbol >= 29) {
+ return false;
+ }
+
int length = length_size_base[symbol] +
Bitstream_next_bits(bitstream, length_extra_bits[symbol]);
symbol = huffman_table_decode(distance_table->symbols,
@@ -207,14 +211,13 @@ bool deflate_decompress_(Bitstream *bitstream,
return false;
}
- int distance =
- distance_offset_base[symbol] +
+ int distance_increment =
Bitstream_next_bits(bitstream, distance_extra_bits[symbol]);
- while (length > 0) {
+ unsigned distance = distance_offset_base[symbol] + distance_increment;
+ while (length--) {
size_t output_buffer_length = OutputBuffer_length(output);
- OutputBuffer_push(
- output, (char)output->buffer[output_buffer_length - distance]);
- length--;
+ OutputBuffer_push(output,
+ output->buffer[output_buffer_length - distance]);
}
}
}
@@ -230,6 +233,7 @@ bool deflate_decompress(Bitstream *bitstream, OutputBuffer *output) {
while (!b_final) {
LPNG_LOG_DBG0("Parse deflate block");
b_final = Bitstream_next_bits(bitstream, BFINAL_LENGTH_BITS);
+ LPNG_LOG_DBG("Final block: %d", b_final);
const uint8_t b_type = Bitstream_next_bits(bitstream, BTYPE_LENGTH_BITS);
if (b_type == DeflateBlockType_NoCompression) {
LPNG_LOG_ERR0("Uncompressed deflate blocks aren't supported");
@@ -391,8 +395,8 @@ uint8_t *zlib_decompress(const uint8_t *compressed_data_buffer,
return NULL;
}
- size_t adler32_offset = bitstream.current_byte_index;
- if (bitstream.current_bit_offset % 8 != 0) {
+ size_t adler32_offset = bitstream.byte_offset;
+ if (bitstream.bit_index % 8 != 0) {
adler32_offset++;
}
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