X-Git-Url: https://git.sesse.net/?p=fjl;a=blobdiff_plain;f=driver.c;h=94cce90332e7df8186c83b0aa311ef3afec61d6f;hp=04e236912ca45d56bc4f1a34f16b3c04185112d9;hb=HEAD;hpb=4f8fc834df5380baab004c708c477e1189e1cd33

diff --git a/driver.c b/driver.c
index 04e2369..94cce90 100644
--- a/driver.c
+++ b/driver.c
@@ -5,22 +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 num_blocks_horizontal, num_blocks_vertical;
-	uint32_t qvalues[256][DCTSIZE2];
-	void* idct_data[256];
-	uint8_t* pixel_data[256];
-};
-
 ssize_t stdio_read(void* userdata, uint8_t* buf, size_t count) 
 {
 	return fread(buf, 1, count, (FILE*)userdata);
@@ -103,13 +92,49 @@ void read_sof(struct byte_source* source, struct jpeg_image* image)
 
 		unsigned width = image->num_blocks_horizontal * image->hsample[c] * DCTSIZE;
 		unsigned height = image->num_blocks_vertical * image->vsample[c] * DCTSIZE;
+		image->stride[c] = width;
 		image->pixel_data[c] = (uint8_t*)malloc(width * height);
 		assert(image->pixel_data[c] != NULL);
+		image->pixel_write_pointer[c] = image->pixel_data[c];
 
 		fprintf(stderr, "Component %u: allocating %d x %d\n", c, width, height);
 	}
 }
 
+void decode_ac_coefficients(const struct huffman_table* tbl, struct bit_source* bits, int16_t* coeff)
+{
+	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];
+
+		if (code == AC_DEHUF_SLOW_PATH) {
+			unsigned rs = read_huffman_symbol_no_refill(tbl, bits);
+			if (rs == 0x00) {
+				/* end of block */
+				break;
+			}
+
+			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 {
+			assert(bits->bits_available >= length);
+			read_bits(bits, length);
+			possibly_refill(bits, DEHUF_AC_TABLE_BITS);
+
+			assert(r >= 1);
+			i += r;
+			coeff[unzigzag[i]] = code;
+		}
+	}
+}
+
 void read_scan(struct byte_source* source, struct jpeg_image* image, huffman_tables_t* tables)
 {
 	unsigned len = read_uint16(byte_source_input_func, source);
@@ -154,11 +179,12 @@ void read_scan(struct byte_source* source, struct jpeg_image* image, huffman_tab
 	while (!bits.source_eof) {
 		for (unsigned c = 0; c < num_components; ++c) {
 			unsigned cn = component_num[c];
-			unsigned stride = image->num_blocks_horizontal * image->hsample[cn] * DCTSIZE;
 			assert(image->idct_data[image->qtable[cn]] != NULL);
-			
-			for (unsigned local_yb = 0; local_yb < image->vsample[cn]; ++local_yb) {
-				for (unsigned local_xb = 0; local_xb < image->hsample[cn]; ++local_xb) {
+
+			uint8_t* pixel_write_pointer_y = image->pixel_write_pointer[cn];
+			for (unsigned local_yb = 0; local_yb < image->vsample[cn]; ++local_yb, pixel_write_pointer_y += image->stride[cn] * DCTSIZE) {
+				uint8_t* pixel_write_pointer = pixel_write_pointer_y;
+				for (unsigned local_xb = 0; local_xb < image->hsample[cn]; ++local_xb, pixel_write_pointer += DCTSIZE) {
 					const struct huffman_table* dc_table = &((*tables)[DC_CLASS][dc_huffman_table[c]]);
 					const struct huffman_table* ac_table = &((*tables)[AC_CLASS][ac_huffman_table[c]]);
 
@@ -169,52 +195,30 @@ void read_scan(struct byte_source* source, struct jpeg_image* image, huffman_tab
 					
 					int16_t coeff[DCTSIZE2] = { 0 };
 					coeff[0] = last_dc[c];
+					decode_ac_coefficients(ac_table, &bits, coeff);
 
-					// decode AC components
-					for (unsigned i = 1; i < DCTSIZE2; ++i) {
-						unsigned rs = read_huffman_symbol(ac_table, &bits);
-						unsigned r = rs >> 4;
-						unsigned s = rs & 0xf;
-
-						if (rs == 0x00) {
-							/* end of block */
-							break;
-						}
-						if (rs == 0xf0) {
-							/* 16 zero coefficients */
-							i += 15;
-							continue;
-						}
-						i += r;
-
-						possibly_refill(&bits, s);
-						coeff[unzigzag[i]] = extend(read_bits(&bits, s), s);
-					}
-			
 					uint8_t pixdata[DCTSIZE2];	
 					idct_choice(coeff, image->idct_data[image->qtable[cn]], pixdata);
 
-					unsigned real_x = (mcu_x * image->hsample[cn] + local_xb) * DCTSIZE;
-					unsigned real_y = (mcu_y * image->vsample[cn] + local_yb) * DCTSIZE;
-					uint8_t* dest_pixdata = image->pixel_data[cn] + real_y * stride + real_x;
-					for (unsigned y = 0; y < DCTSIZE; ++y, dest_pixdata += stride) {
+					uint8_t* dest_pixdata = pixel_write_pointer;
+					for (unsigned y = 0; y < DCTSIZE; ++y, dest_pixdata += image->stride[cn]) {
 						memcpy(dest_pixdata, pixdata + y * DCTSIZE, DCTSIZE);
 					}
 				}
 			}
+			image->pixel_write_pointer[cn] += DCTSIZE * image->hsample[cn];
 		}
-		
+	
 		if (++mcu_x == image->num_blocks_horizontal) {
 			++mcu_y;
 			mcu_x = 0;
-
-			// Some debug code.
-			const int c = 1;
+		
+			for (unsigned c = 0; c < num_components; ++c) {
+				unsigned cn = component_num[c];
+				image->pixel_write_pointer[cn] += (image->vsample[cn] * DCTSIZE - 1) * image->stride[cn];
+			}
 			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;
 			}
 		}
 	}
@@ -238,14 +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;
 
@@ -283,25 +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);
@@ -309,3 +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);
+}