X-Git-Url: https://git.sesse.net/?p=fjl;a=blobdiff_plain;f=driver.c;h=94cce90332e7df8186c83b0aa311ef3afec61d6f;hp=c5ae87e3b003cc2b060ccfe3fa1571ff817a2246;hb=HEAD;hpb=a1596fbb6a92217ff5eb57600b36a9d695ca1ae8

diff --git a/driver.c b/driver.c
index c5ae87e..94cce90 100644
--- a/driver.c
+++ b/driver.c
@@ -5,24 +5,11 @@
 #include "bytesource.h"
 #include "choice.h"
 #include "dehuff.h"
+#include "driver.h"
 #include "idct.h"
 #include "input.h"
 #include "zigzag.h"
 
-struct jpeg_image {
-	unsigned precision;
-	unsigned width, height;
-	unsigned num_components;
-	unsigned hsample[256], vsample[256], qtable[256];
-	unsigned max_hsample, max_vsample;
-	unsigned stride[256];
-	unsigned num_blocks_horizontal, num_blocks_vertical;
-	uint32_t qvalues[256][DCTSIZE2];
-	void* idct_data[256];
-	uint8_t* pixel_data[256];
-	uint8_t* pixel_write_pointer[256];
-};
-
 ssize_t stdio_read(void* userdata, uint8_t* buf, size_t count) 
 {
 	return fread(buf, 1, count, (FILE*)userdata);
@@ -116,45 +103,33 @@ void read_sof(struct byte_source* source, struct jpeg_image* image)
 
 void decode_ac_coefficients(const struct huffman_table* tbl, struct bit_source* bits, int16_t* coeff)
 {
-	for (unsigned i = 1; i < DCTSIZE2; ++i) {
-		possibly_refill(bits, DEHUF_AC_TABLE_BITS);
+	possibly_refill(bits, DEHUF_AC_TABLE_BITS);
+	for (unsigned i = 0; i < DCTSIZE2 - 1; ) {
 		unsigned lookup = peek_bits(bits, DEHUF_AC_TABLE_BITS);
 		int code = tbl->ac_table_codes[lookup];
+		unsigned length = tbl->ac_table_length[lookup];
+		unsigned r = tbl->ac_table_skip[lookup];
 
-		assert(length == AC_DEHUF_SLOW_PATH || (length > 0 && length <= DEHUF_AC_TABLE_BITS));
-
-		if (__builtin_expect(code == AC_DEHUF_SLOW_PATH, 0)) {
+		if (code == AC_DEHUF_SLOW_PATH) {
 			unsigned rs = read_huffman_symbol_no_refill(tbl, bits);
-			unsigned r = rs >> 4;
-			unsigned s = rs & 0xf;
-			i += r;
-			possibly_refill(bits, s);
-
 			if (rs == 0x00) {
-				assert(code == AC_DEHUF_SLOW_PATH || code == AC_END_OF_BLOCK);
 				/* end of block */
 				break;
 			}
-			if (rs == 0xf0) {
-				assert(code == AC_DEHUF_SLOW_PATH || code == AC_SIXTEEN_ZEROS);
-				/* 16 zero coefficients */
-				continue;
-			}
 
+			unsigned r = rs >> 4;
+			unsigned s = rs & 0xf;
+			i += r + 1;
+			possibly_refill(bits, s);
 			coeff[unzigzag[i]] = extend(read_bits(bits, s), s);
+			possibly_refill(bits, DEHUF_AC_TABLE_BITS);
 		} else {
-			int length = tbl->ac_table_length[lookup];
-			int r = tbl->ac_table_skip[lookup];
-			assert(r >= 0);
-			i += r;
 			assert(bits->bits_available >= length);
 			read_bits(bits, length);
-			if (code == AC_END_OF_BLOCK) {
-				break;
-			}
-			if (code == AC_SIXTEEN_ZEROS) {
-				continue;
-			}
+			possibly_refill(bits, DEHUF_AC_TABLE_BITS);
+
+			assert(r >= 1);
+			i += r;
 			coeff[unzigzag[i]] = code;
 		}
 	}
@@ -242,14 +217,8 @@ void read_scan(struct byte_source* source, struct jpeg_image* image, huffman_tab
 				unsigned cn = component_num[c];
 				image->pixel_write_pointer[cn] += (image->vsample[cn] * DCTSIZE - 1) * image->stride[cn];
 			}
-
-			// Some debug code.
-			const int c = 1;
 			if (mcu_y == image->num_blocks_vertical) {
-				unsigned stride = image->num_blocks_horizontal * image->hsample[c] * DCTSIZE;
-				unsigned height = image->num_blocks_vertical * image->vsample[c] * DCTSIZE;
-				printf("P5\n%u %u\n255\n", stride, height);
-				fwrite(image->pixel_data[c], stride * height, 1, stdout);
+				return;
 			}
 		}
 	}
@@ -273,14 +242,12 @@ void skip_segment(struct byte_source* source)
 	}
 }
 	
-int main(void)
+void read_jpeg(struct jpeg_image* jpeg, FILE *input)
 {
-	struct jpeg_image jpeg;
-	memset(&jpeg, 0, sizeof(jpeg));
-	init_choices();
-
+	memset(jpeg, 0, sizeof(*jpeg));
+	
 	struct byte_source source;
-	init_byte_source(&source, stdio_read, stdin);
+	init_byte_source(&source, stdio_read, input);
 
 	huffman_tables_t tables;
 
@@ -318,25 +285,25 @@ int main(void)
 			break;
 		case 0xdb:
 			/* DQT */
-			read_dqt(&source, &jpeg);
+			read_dqt(&source, jpeg);
 			break;
 		case 0xc0:
 			/* SOF0 (baseline DCT, Huffman encoded) */
-			read_sof(&source, &jpeg);
+			read_sof(&source, jpeg);
 			break;
 		case 0xd8:
 			/* SOI */
 			break;
 		case 0xd9:
 			/* EOI */
-			exit(0);
+			return;
 		case 0xc4:
 			/* DHT (define Huffman tables) */
 			read_huffman_tables(&tables, byte_source_input_func, &source);
 			break;
 		case 0xda:
 			/* SOS (start of scan) */
-			read_scan(&source, &jpeg, &tables);
+			read_scan(&source, jpeg, &tables);
 			break;
 		default:
 			fprintf(stderr, "Error: Unknown marker 0x%02x\n", m2);
@@ -344,3 +311,18 @@ int main(void)
 		}
 	}
 }
+	
+int main(void)
+{
+	init_choices();
+
+	struct jpeg_image jpeg;
+	read_jpeg(&jpeg, stdin);
+
+	// Some debug code.
+	const int c = 1;
+	unsigned stride = jpeg.num_blocks_horizontal * jpeg.hsample[c] * DCTSIZE;
+	unsigned height = jpeg.num_blocks_vertical * jpeg.vsample[c] * DCTSIZE;
+	printf("P5\n%u %u\n255\n", stride, height);
+	fwrite(jpeg.pixel_data[c], stride * height, 1, stdout);
+}