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-rw-r--r--.gitignore4
-rw-r--r--lisiblepng-bin/meson.build1
-rw-r--r--lisiblepng-bin/src/main.c33
-rw-r--r--lisiblepng/meson.build3
-rw-r--r--lisiblepng/src/assert.h15
-rw-r--r--lisiblepng/src/bitstream.c54
-rw-r--r--lisiblepng/src/bitstream.h20
-rw-r--r--lisiblepng/src/deflate.c56
-rw-r--r--lisiblepng/src/deflate.h11
-rw-r--r--lisiblepng/src/lisiblepng.c334
-rw-r--r--lisiblepng/src/lisiblepng.h15
-rw-r--r--lisiblepng/src/log.h9
-rw-r--r--meson.build4
13 files changed, 559 insertions, 0 deletions
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..e0b0981
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,4 @@
+.cache/
+compile_commands.json
+png_suite/
+build/
diff --git a/lisiblepng-bin/meson.build b/lisiblepng-bin/meson.build
new file mode 100644
index 0000000..64a5cc1
--- /dev/null
+++ b/lisiblepng-bin/meson.build
@@ -0,0 +1 @@
+lisiblepng_bin = executable('lisiblepng', 'src/main.c', dependencies: [lisiblepng_dep])
diff --git a/lisiblepng-bin/src/main.c b/lisiblepng-bin/src/main.c
new file mode 100644
index 0000000..7979326
--- /dev/null
+++ b/lisiblepng-bin/src/main.c
@@ -0,0 +1,33 @@
+#include <errno.h>
+#include <lisiblepng.h>
+#include <log.h>
+#include <string.h>
+
+int main(int argc, char **argv) {
+ if (argc != 2) {
+ LOG0("Usage: lisiblepng <png filepath>");
+ return 1;
+ }
+
+ const char *png_filepath = argv[1];
+ FILE *png_file = fopen(png_filepath, "r");
+ if (!png_file) {
+ const char *error_message = strerror(errno);
+ LOGN("Couldn't open PNG file: %s", error_message);
+ goto err;
+ }
+
+ Png *png = lis_Png_parse(png_file);
+ lis_Png_dump_ppm(png);
+ lis_Png_destroy(png);
+
+ if (fclose(png_file) != 0) {
+ const char *error_message = strerror(errno);
+ LOGN("Couldn't close PNG file: %s", error_message);
+ goto err;
+ }
+
+ return 0;
+err:
+ return 1;
+}
diff --git a/lisiblepng/meson.build b/lisiblepng/meson.build
new file mode 100644
index 0000000..224011a
--- /dev/null
+++ b/lisiblepng/meson.build
@@ -0,0 +1,3 @@
+lisiblepng_incdir = include_directories('src/')
+lisiblepng_lib = library('lisiblepng', 'src/lisiblepng.c', 'src/deflate.c', 'src/bitstream.c')
+lisiblepng_dep = declare_dependency(include_directories: lisiblepng_incdir, link_with: [lisiblepng_lib])
diff --git a/lisiblepng/src/assert.h b/lisiblepng/src/assert.h
new file mode 100644
index 0000000..7d41b57
--- /dev/null
+++ b/lisiblepng/src/assert.h
@@ -0,0 +1,15 @@
+#ifndef LISIBLE_PNG_ASSET_H
+#define LISIBLE_PNG_ASSET_H
+
+#include "log.h"
+
+#define ASSERT(predicate) \
+ do { \
+ if (!(predicate)) { \
+ LOGN("Assertion failed in %s:%d:\n\t%s", __FILE__, __LINE__, \
+ #predicate); \
+ exit(1); \
+ } \
+ } while (0)
+
+#endif // LISIBLE_PNG_ASSET_H
diff --git a/lisiblepng/src/bitstream.c b/lisiblepng/src/bitstream.c
new file mode 100644
index 0000000..b34a890
--- /dev/null
+++ b/lisiblepng/src/bitstream.c
@@ -0,0 +1,54 @@
+#include "bitstream.h"
+#include "assert.h"
+
+#define MAX(x, y) (((x) > (y)) ? (x) : (y))
+#define MIN(x, y) (((x) < (y)) ? (x) : (y))
+
+void Bitstream_init(Bitstream *bitstream, const uint8_t *data,
+ size_t data_size) {
+ ASSERT(bitstream != NULL);
+ ASSERT(data != NULL);
+ bitstream->data = data;
+ bitstream->data_size = data_size;
+ bitstream->current_byte_index = 0;
+ bitstream->current_bit_offset = 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;
+}
+
+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_byte_index +
+ (bitstream->current_bit_offset + bit_count) % 8 <=
+ 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;
+ }
+
+ return (val & ((1 << bit_count) - 1));
+}
diff --git a/lisiblepng/src/bitstream.h b/lisiblepng/src/bitstream.h
new file mode 100644
index 0000000..72d8295
--- /dev/null
+++ b/lisiblepng/src/bitstream.h
@@ -0,0 +1,20 @@
+#ifndef CUTTERENG_BITSTREAM_H
+#define CUTTERENG_BITSTREAM_H
+
+#include <stdint.h>
+#include <stdlib.h>
+
+typedef struct {
+ const uint8_t *data;
+ size_t data_size;
+
+ size_t current_byte_index;
+ uint8_t current_bit_offset;
+} Bitstream;
+
+void Bitstream_init(Bitstream *bitstream, const uint8_t *data,
+ size_t data_size);
+void Bitstream_skip(Bitstream *bitstream, size_t bit_count);
+uint16_t Bitstream_next_bits(Bitstream *bitstream, int bit_count);
+
+#endif // CUTTERENG_BITSTREAM_H
diff --git a/lisiblepng/src/deflate.c b/lisiblepng/src/deflate.c
new file mode 100644
index 0000000..3f8ce2e
--- /dev/null
+++ b/lisiblepng/src/deflate.c
@@ -0,0 +1,56 @@
+#include "deflate.h"
+#include "assert.h"
+#include "bitstream.h"
+
+#define CM_LENGTH_BITS 4
+#define CINFO_LENGTH_BITS 4
+#define FCHECK_LENGTH_BITS 5
+#define FDICT_LENGTH_BITS 1
+#define FLEVEL_LENGTH_BITS 2
+
+bool deflate_decompress(Bitstream *bitstream);
+
+bool zlib_decompress(const uint8_t *compressed_data_buffer,
+ const size_t compressed_data_length) {
+ ASSERT(compressed_data_buffer != NULL);
+
+ Bitstream bitstream;
+ Bitstream_init(&bitstream, compressed_data_buffer, compressed_data_length);
+
+ uint16_t cm = Bitstream_next_bits(&bitstream, CM_LENGTH_BITS);
+ uint16_t cinfo = Bitstream_next_bits(&bitstream, CINFO_LENGTH_BITS);
+ uint16_t fcheck = Bitstream_next_bits(&bitstream, FCHECK_LENGTH_BITS);
+ uint16_t fdict = Bitstream_next_bits(&bitstream, FDICT_LENGTH_BITS);
+ uint16_t flevel = Bitstream_next_bits(&bitstream, FLEVEL_LENGTH_BITS);
+
+ LOGN("zlib informations:\n"
+ "- CM (compression method): %d\n"
+ "- CINFO (compression info): %d\n"
+ "- FCHECK (check bits for CMF and FLG): %d\n"
+ "- FDICT (preset dictionary): %d\n"
+ "- FLEVEL (compression level): %d",
+ cm, cinfo, fcheck, fdict, flevel);
+ uint16_t cmf = bitstream.data[0];
+ uint16_t flg = bitstream.data[1];
+ if ((cmf * 256 + flg) % 31 != 0) {
+ LOG0("fcheck validation failed");
+ return false;
+ }
+
+ uint32_t dictionary_identifier = 0;
+ if (fdict != 0) {
+ uint16_t dictionary_identifier_0 = Bitstream_next_bits(&bitstream, 16);
+ uint16_t dictionary_identifier_1 = Bitstream_next_bits(&bitstream, 16);
+ dictionary_identifier =
+ (dictionary_identifier_0 << 0) + (dictionary_identifier_1 << 16);
+ LOGN("Dictionary identifier: %d", dictionary_identifier);
+ }
+
+ if (!deflate_decompress(&bitstream)) {
+ return false;
+ }
+
+ // TODO adler32 checksum
+
+ return true;
+}
diff --git a/lisiblepng/src/deflate.h b/lisiblepng/src/deflate.h
new file mode 100644
index 0000000..e40f816
--- /dev/null
+++ b/lisiblepng/src/deflate.h
@@ -0,0 +1,11 @@
+#ifndef LISIBLE_PNG_DEFLATE_H
+#define LISIBLE_PNG_DEFLATE_H
+
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdlib.h>
+
+bool zlib_decompress(const uint8_t *compressed_data_buffer,
+ const size_t compressed_data_length);
+
+#endif // LISIBLE_PNG_DEFLATE_H
diff --git a/lisiblepng/src/lisiblepng.c b/lisiblepng/src/lisiblepng.c
new file mode 100644
index 0000000..3dfda24
--- /dev/null
+++ b/lisiblepng/src/lisiblepng.c
@@ -0,0 +1,334 @@
+#include "lisiblepng.h"
+#include "assert.h"
+#include "deflate.h"
+#include "log.h"
+#include <errno.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#define PNG_SIGNATURE_LENGTH 8
+const uint8_t PNG_SIGNATURE[PNG_SIGNATURE_LENGTH] = {0x89, 0x50, 0x4E, 0x47,
+ 0x0D, 0x0A, 0x1A, 0x0A};
+#define IHDR_CHUNK_TYPE 0x49484452
+#define IEND_CHUNK_TYPE 0x49454e44
+#define IDAT_CHUNK_TYPE 0x49444154
+
+const uint32_t CRC32_TABLE[256] = {
+ 0x00000000, 0x77073096, 0xEE0E612C, 0x990951BA, 0x076DC419, 0x706AF48F,
+ 0xE963A535, 0x9E6495A3, 0x0EDB8832, 0x79DCB8A4, 0xE0D5E91E, 0x97D2D988,
+ 0x09B64C2B, 0x7EB17CBD, 0xE7B82D07, 0x90BF1D91, 0x1DB71064, 0x6AB020F2,
+ 0xF3B97148, 0x84BE41DE, 0x1ADAD47D, 0x6DDDE4EB, 0xF4D4B551, 0x83D385C7,
+ 0x136C9856, 0x646BA8C0, 0xFD62F97A, 0x8A65C9EC, 0x14015C4F, 0x63066CD9,
+ 0xFA0F3D63, 0x8D080DF5, 0x3B6E20C8, 0x4C69105E, 0xD56041E4, 0xA2677172,
+ 0x3C03E4D1, 0x4B04D447, 0xD20D85FD, 0xA50AB56B, 0x35B5A8FA, 0x42B2986C,
+ 0xDBBBC9D6, 0xACBCF940, 0x32D86CE3, 0x45DF5C75, 0xDCD60DCF, 0xABD13D59,
+ 0x26D930AC, 0x51DE003A, 0xC8D75180, 0xBFD06116, 0x21B4F4B5, 0x56B3C423,
+ 0xCFBA9599, 0xB8BDA50F, 0x2802B89E, 0x5F058808, 0xC60CD9B2, 0xB10BE924,
+ 0x2F6F7C87, 0x58684C11, 0xC1611DAB, 0xB6662D3D, 0x76DC4190, 0x01DB7106,
+ 0x98D220BC, 0xEFD5102A, 0x71B18589, 0x06B6B51F, 0x9FBFE4A5, 0xE8B8D433,
+ 0x7807C9A2, 0x0F00F934, 0x9609A88E, 0xE10E9818, 0x7F6A0DBB, 0x086D3D2D,
+ 0x91646C97, 0xE6635C01, 0x6B6B51F4, 0x1C6C6162, 0x856530D8, 0xF262004E,
+ 0x6C0695ED, 0x1B01A57B, 0x8208F4C1, 0xF50FC457, 0x65B0D9C6, 0x12B7E950,
+ 0x8BBEB8EA, 0xFCB9887C, 0x62DD1DDF, 0x15DA2D49, 0x8CD37CF3, 0xFBD44C65,
+ 0x4DB26158, 0x3AB551CE, 0xA3BC0074, 0xD4BB30E2, 0x4ADFA541, 0x3DD895D7,
+ 0xA4D1C46D, 0xD3D6F4FB, 0x4369E96A, 0x346ED9FC, 0xAD678846, 0xDA60B8D0,
+ 0x44042D73, 0x33031DE5, 0xAA0A4C5F, 0xDD0D7CC9, 0x5005713C, 0x270241AA,
+ 0xBE0B1010, 0xC90C2086, 0x5768B525, 0x206F85B3, 0xB966D409, 0xCE61E49F,
+ 0x5EDEF90E, 0x29D9C998, 0xB0D09822, 0xC7D7A8B4, 0x59B33D17, 0x2EB40D81,
+ 0xB7BD5C3B, 0xC0BA6CAD, 0xEDB88320, 0x9ABFB3B6, 0x03B6E20C, 0x74B1D29A,
+ 0xEAD54739, 0x9DD277AF, 0x04DB2615, 0x73DC1683, 0xE3630B12, 0x94643B84,
+ 0x0D6D6A3E, 0x7A6A5AA8, 0xE40ECF0B, 0x9309FF9D, 0x0A00AE27, 0x7D079EB1,
+ 0xF00F9344, 0x8708A3D2, 0x1E01F268, 0x6906C2FE, 0xF762575D, 0x806567CB,
+ 0x196C3671, 0x6E6B06E7, 0xFED41B76, 0x89D32BE0, 0x10DA7A5A, 0x67DD4ACC,
+ 0xF9B9DF6F, 0x8EBEEFF9, 0x17B7BE43, 0x60B08ED5, 0xD6D6A3E8, 0xA1D1937E,
+ 0x38D8C2C4, 0x4FDFF252, 0xD1BB67F1, 0xA6BC5767, 0x3FB506DD, 0x48B2364B,
+ 0xD80D2BDA, 0xAF0A1B4C, 0x36034AF6, 0x41047A60, 0xDF60EFC3, 0xA867DF55,
+ 0x316E8EEF, 0x4669BE79, 0xCB61B38C, 0xBC66831A, 0x256FD2A0, 0x5268E236,
+ 0xCC0C7795, 0xBB0B4703, 0x220216B9, 0x5505262F, 0xC5BA3BBE, 0xB2BD0B28,
+ 0x2BB45A92, 0x5CB36A04, 0xC2D7FFA7, 0xB5D0CF31, 0x2CD99E8B, 0x5BDEAE1D,
+ 0x9B64C2B0, 0xEC63F226, 0x756AA39C, 0x026D930A, 0x9C0906A9, 0xEB0E363F,
+ 0x72076785, 0x05005713, 0x95BF4A82, 0xE2B87A14, 0x7BB12BAE, 0x0CB61B38,
+ 0x92D28E9B, 0xE5D5BE0D, 0x7CDCEFB7, 0x0BDBDF21, 0x86D3D2D4, 0xF1D4E242,
+ 0x68DDB3F8, 0x1FDA836E, 0x81BE16CD, 0xF6B9265B, 0x6FB077E1, 0x18B74777,
+ 0x88085AE6, 0xFF0F6A70, 0x66063BCA, 0x11010B5C, 0x8F659EFF, 0xF862AE69,
+ 0x616BFFD3, 0x166CCF45, 0xA00AE278, 0xD70DD2EE, 0x4E048354, 0x3903B3C2,
+ 0xA7672661, 0xD06016F7, 0x4969474D, 0x3E6E77DB, 0xAED16A4A, 0xD9D65ADC,
+ 0x40DF0B66, 0x37D83BF0, 0xA9BCAE53, 0xDEBB9EC5, 0x47B2CF7F, 0x30B5FFE9,
+ 0xBDBDF21C, 0xCABAC28A, 0x53B39330, 0x24B4A3A6, 0xBAD03605, 0xCDD70693,
+ 0x54DE5729, 0x23D967BF, 0xB3667A2E, 0xC4614AB8, 0x5D681B02, 0x2A6F2B94,
+ 0xB40BBE37, 0xC30C8EA1, 0x5A05DF1B, 0x2D02EF8D};
+
+struct Png {
+ const uint8_t *data;
+};
+
+typedef struct {
+ FILE *stream;
+#ifdef LISIBLE_PNG_COMPUTE_CRC
+ uint32_t computed_crc;
+#endif // LISIBLE_PNG_COMPUTE_CRC
+} DeflateDecompressor;
+
+void DeflateDecompressor_init(DeflateDecompressor *ctx, FILE *stream) {
+ ASSERT(ctx != NULL);
+ ASSERT(stream != NULL);
+ ctx->stream = stream;
+}
+
+void ParsingContext_crc_reset(DeflateDecompressor *ctx) {
+ ASSERT(ctx != NULL);
+#ifdef LISIBLE_PNG_COMPUTE_CRC
+ ctx->computed_crc = 0xFFFFFFFFu;
+#endif // LISIBLE_PNG_COMPUTE_CRC
+}
+
+#ifdef LISIBLE_PNG_COMPUTE_CRC
+uint32_t ParsingContext_computed_crc(DeflateDecompressor *ctx) {
+ ASSERT(ctx != NULL);
+ return ctx->computed_crc ^ 0xFFFFFFFFu;
+}
+#endif // LISIBLE_PNG_COMPUTE_CRC
+
+long ParsingContext_cursor_position(DeflateDecompressor *ctx) {
+ ASSERT(ctx != NULL);
+ return ftell(ctx->stream);
+}
+
+bool ParsingContext_skip_bytes(DeflateDecompressor *ctx, size_t byte_count) {
+ ASSERT(ctx != NULL);
+ if (fseek(ctx->stream, byte_count, SEEK_CUR) != 0) {
+ LOGN("Couldn't skip bytes: %s", strerror(errno));
+ return false;
+ }
+
+ return true;
+}
+
+bool ParsingContext_parse_bytes(DeflateDecompressor *ctx, size_t byte_count,
+ uint8_t *output_buffer) {
+ ASSERT(ctx != NULL);
+ ASSERT(output_buffer != NULL);
+ if (fread(output_buffer, 1, byte_count, ctx->stream) < byte_count) {
+ LOG0("Couldn't parse bytes, EOF reached");
+ return false;
+ }
+
+#ifdef LISIBLE_PNG_COMPUTE_CRC
+ for (size_t i = 0; i < byte_count; i++) {
+ const uint32_t index = (ctx->computed_crc ^ output_buffer[i]) & 0xFF;
+ ctx->computed_crc = (ctx->computed_crc >> 8) ^ CRC32_TABLE[index];
+ }
+#endif // LISIBLE_PNG_COMPUTE_CRC
+
+ return true;
+}
+
+bool ParsingContext_parse_uint32_t(DeflateDecompressor *ctx,
+ uint32_t *output_u32) {
+ ASSERT(ctx != NULL);
+ ASSERT(output_u32 != NULL);
+ uint8_t bytes[4];
+ if (!ParsingContext_parse_bytes(ctx, 4, bytes)) {
+ return false;
+ }
+ *output_u32 =
+ (bytes[0] << 24) + (bytes[1] << 16) + (bytes[2] << 8) + bytes[3];
+ return true;
+}
+
+bool ParsingContext_parse_uint8_t(DeflateDecompressor *ctx,
+ uint8_t *output_u8) {
+ ASSERT(ctx != NULL);
+ ASSERT(output_u8 != NULL);
+ if (!ParsingContext_parse_bytes(ctx, 1, output_u8)) {
+ return false;
+ }
+ return true;
+}
+
+bool matches_png_signature(uint8_t signature[PNG_SIGNATURE_LENGTH]) {
+ return memcmp(signature, PNG_SIGNATURE, PNG_SIGNATURE_LENGTH) == 0;
+}
+
+#define PARSE_FIELD(type, field) \
+ do { \
+ if (!ParsingContext_parse_##type(ctx, &field)) { \
+ return false; \
+ } \
+ } while (0)
+
+typedef struct {
+ uint32_t width;
+ uint32_t height;
+ uint8_t bit_depth;
+ uint8_t colour_type;
+ uint8_t compression_method;
+ uint8_t filter_method;
+ uint8_t interlace_method;
+} ImageHeader;
+
+typedef struct {
+ size_t length;
+ uint8_t *data;
+} ImageData;
+
+void ImageHeader_print_image_header(const ImageHeader *image_header) {
+ ASSERT(image_header != NULL);
+ LOGN("Image header:\n"
+ "- dimensions: %dx%d\n"
+ "- bit depth: %d\n"
+ "- colour type: %d\n"
+ "- compression method: %d\n"
+ "- filter method: %d\n"
+ "- interlace method: %d",
+ image_header->width, image_header->height, image_header->bit_depth,
+ image_header->colour_type, image_header->compression_method,
+ image_header->filter_method, image_header->interlace_method);
+}
+
+bool ParsingContext_validate_crc_if_required(DeflateDecompressor *ctx) {
+#ifdef LISIBLE_PNG_COMPUTE_CRC
+ uint32_t computed_crc = ParsingContext_computed_crc(ctx);
+ uint32_t crc;
+ PARSE_FIELD(uint32_t, crc);
+ if (computed_crc != crc) {
+ LOG0("Invalid CRC checksum");
+ return false;
+ }
+#else
+ ParsingContext_skip_bytes(ctx, sizeof(uint32_t));
+#endif
+
+ return true;
+}
+
+bool parse_IHDR_chunk(DeflateDecompressor *ctx, ImageHeader *image_header) {
+ ASSERT(ctx != NULL);
+ ASSERT(image_header != NULL);
+
+ uint32_t length;
+ PARSE_FIELD(uint32_t, length);
+
+ ParsingContext_crc_reset(ctx);
+
+ uint32_t type;
+ PARSE_FIELD(uint32_t, type);
+ if (type != IHDR_CHUNK_TYPE) {
+ LOG0("Expected IHDR chunk");
+ return false;
+ }
+
+ long data_start = ParsingContext_cursor_position(ctx);
+ PARSE_FIELD(uint32_t, image_header->width);
+ PARSE_FIELD(uint32_t, image_header->height);
+ PARSE_FIELD(uint8_t, image_header->bit_depth);
+ PARSE_FIELD(uint8_t, image_header->colour_type);
+ PARSE_FIELD(uint8_t, image_header->compression_method);
+ PARSE_FIELD(uint8_t, image_header->filter_method);
+ PARSE_FIELD(uint8_t, image_header->interlace_method);
+ long read_data_length = ParsingContext_cursor_position(ctx) - data_start;
+ ASSERT(read_data_length == length);
+
+ if (!ParsingContext_validate_crc_if_required(ctx)) {
+ return false;
+ }
+
+ return true;
+}
+
+bool parse_IDAT_chunk(DeflateDecompressor *ctx, uint32_t data_length,
+ ImageData *image_data) {
+ ASSERT(ctx != NULL);
+ ASSERT(image_data != NULL);
+
+ image_data->data = realloc(image_data->data, data_length);
+ ParsingContext_parse_bytes(ctx, data_length,
+ &image_data->data[image_data->length]);
+ image_data->length = data_length;
+
+ if (!ParsingContext_validate_crc_if_required(ctx)) {
+ return false;
+ }
+
+ return true;
+}
+
+uint32_t uint32_t_to_le(uint32_t value) {
+ char *value_bytes = (char *)&value;
+ return (value_bytes[0] << 24) + (value_bytes[1] << 16) +
+ (value_bytes[2] << 8) + value_bytes[3];
+}
+
+Png *lis_Png_parse(FILE *stream) {
+ Png *png = malloc(sizeof(Png));
+ DeflateDecompressor ctx;
+
+ DeflateDecompressor_init(&ctx, stream);
+ uint8_t parsed_png_signature[PNG_SIGNATURE_LENGTH];
+ if (!ParsingContext_parse_bytes(&ctx, PNG_SIGNATURE_LENGTH,
+ parsed_png_signature)) {
+ LOG0("Couldn't parse signature");
+ goto err;
+ }
+
+ if (!matches_png_signature(parsed_png_signature)) {
+ LOG0("Invalid signature");
+ goto err;
+ }
+
+ ImageHeader header;
+ if (!parse_IHDR_chunk(&ctx, &header)) {
+ goto err;
+ }
+ ImageHeader_print_image_header(&header);
+
+ ImageData image_data = {0};
+ bool end_reached = false;
+ while (!end_reached) {
+ uint32_t length;
+ if (!ParsingContext_parse_uint32_t(&ctx, &length)) {
+ LOG0("Couldn't parse chunk length");
+ goto cleanup_data;
+ }
+
+ ParsingContext_crc_reset(&ctx);
+ uint32_t type;
+ if (!ParsingContext_parse_uint32_t(&ctx, &type)) {
+ LOG0("Couldn't parse chunk type");
+ goto cleanup_data;
+ }
+
+ uint32_t type_le = uint32_t_to_le(type);
+ LOGN("Parsing %.4s chunk", (char *)&type_le);
+ switch (type) {
+ case IDAT_CHUNK_TYPE:
+ parse_IDAT_chunk(&ctx, length, &image_data);
+ break;
+ case IEND_CHUNK_TYPE:
+ end_reached = true;
+ ParsingContext_skip_bytes(&ctx, sizeof(uint32_t));
+ break;
+ default:
+ LOG0("Unknown chunk type, skipping chunk...");
+ ParsingContext_skip_bytes(&ctx, length + sizeof(uint32_t));
+ break;
+ }
+ }
+
+ LOGN("Data length: %zul", image_data.length);
+ zlib_decompress(image_data.data, image_data.length);
+
+ return png;
+
+cleanup_data:
+ free(image_data.data);
+err:
+ return NULL;
+}
+
+#undef PARSE_FIELD
+void lis_Png_destroy(Png *png) { free(png); }
+void lis_Png_dump_ppm(const Png *png) { ASSERT(png != NULL); }
diff --git a/lisiblepng/src/lisiblepng.h b/lisiblepng/src/lisiblepng.h
new file mode 100644
index 0000000..549e0a4
--- /dev/null
+++ b/lisiblepng/src/lisiblepng.h
@@ -0,0 +1,15 @@
+#ifndef LISIBLE_PNG_H
+#define LISIBLE_PNG_H
+
+#include <stdio.h>
+
+#define LISIBLE_PNG_COMPUTE_CRC
+
+struct Png;
+typedef struct Png Png;
+
+Png *lis_Png_parse(FILE *stream);
+void lis_Png_dump_ppm(const Png *png);
+void lis_Png_destroy(Png *png);
+
+#endif // LISIBLE_PNG_H
diff --git a/lisiblepng/src/log.h b/lisiblepng/src/log.h
new file mode 100644
index 0000000..fba6820
--- /dev/null
+++ b/lisiblepng/src/log.h
@@ -0,0 +1,9 @@
+#ifndef LISIBLE_PNG_LOG_H
+#define LISIBLE_PNG_LOG_H
+
+#include <stdio.h>
+
+#define LOG0(fmt) fprintf(stderr, fmt "\n")
+#define LOGN(fmt, ...) fprintf(stderr, fmt "\n", __VA_ARGS__)
+
+#endif // LISIBLE_PNG_LOG_H
diff --git a/meson.build b/meson.build
new file mode 100644
index 0000000..43f4eb8
--- /dev/null
+++ b/meson.build
@@ -0,0 +1,4 @@
+project('lisiblepng', 'c', default_options: ['c_std=c18', 'warning_level=3'])
+
+subdir('lisiblepng')
+subdir('lisiblepng-bin')
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