X-Git-Url: https://git.sesse.net/?p=fjl;a=blobdiff_plain;f=driver.c;h=616b613f944ee5ae3ba12a69476eb37d9b20a336;hp=aa803d6ed00aa67266495b65df93e6582bc89151;hb=a4009687c73083dd0290285a065740a83e27e855;hpb=9069ae93f3e9e9b44f5f28968f508d09f0711737

diff --git a/driver.c b/driver.c
index aa803d6..616b613 100644
--- a/driver.c
+++ b/driver.c
@@ -15,10 +15,12 @@ struct jpeg_image {
 	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) 
@@ -103,8 +105,10 @@ 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);
 	}
@@ -151,20 +155,21 @@ void read_scan(struct byte_source* source, struct jpeg_image* image, huffman_tab
 		
 	unsigned mcu_x = 0, mcu_y = 0;
 
-	for ( ;; ) {
+	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]]);
 
 					// decode DC component
 					unsigned dc_category = read_huffman_symbol(dc_table, &bits);
-					possibly_refill(&bits, dc_category);
+					possibly_refill(&bits, dc_category + DEHUF_TABLE_BITS);
 					last_dc[c] += extend(read_bits(&bits, dc_category), dc_category);
 					
 					int16_t coeff[DCTSIZE2] = { 0 };
@@ -172,7 +177,7 @@ void read_scan(struct byte_source* source, struct jpeg_image* image, huffman_tab
 
 					// decode AC components
 					for (unsigned i = 1; i < DCTSIZE2; ++i) {
-						unsigned rs = read_huffman_symbol(ac_table, &bits);
+						unsigned rs = read_huffman_symbol_no_refill(ac_table, &bits);
 						unsigned r = rs >> 4;
 						unsigned s = rs & 0xf;
 
@@ -182,40 +187,44 @@ void read_scan(struct byte_source* source, struct jpeg_image* image, huffman_tab
 						}
 						if (rs == 0xf0) {
 							/* 16 zero coefficients */
+							possibly_refill(&bits, DEHUF_TABLE_BITS);
 							i += 15;
 							continue;
 						}
 						i += r;
 
-						possibly_refill(&bits, s);
+						possibly_refill(&bits, s + DEHUF_TABLE_BITS);
 						coeff[unzigzag[i]] = extend(read_bits(&bits, s), s);
 					}
 			
 					uint8_t pixdata[DCTSIZE2];	
 					idct_choice(coeff, image->idct_data[image->qtable[cn]], pixdata);
 
-					for (unsigned y = 0; y < DCTSIZE; ++y) {
-						unsigned real_x = (mcu_x * image->hsample[cn] + local_xb) * DCTSIZE;
-						unsigned real_y = (mcu_y * image->vsample[cn] + local_yb) * DCTSIZE + y;
-					
-						memcpy(image->pixel_data[cn] + real_y * stride + real_x,
-						       pixdata + y * DCTSIZE,
-						       DCTSIZE);
+					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;
+		
+			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];
+			}
 
 			// Some debug code.
 			const int c = 1;
 			if (mcu_y == image->num_blocks_vertical) {
 				unsigned stride = image->num_blocks_horizontal * image->hsample[c] * DCTSIZE;
-				printf("P5\n%u %u\n255\n", stride, image->height);
-				fwrite(image->pixel_data[c], stride * image->height, 1, stdout);
+				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);
 			}
 		}
 	}
@@ -293,6 +302,9 @@ int main(void)
 		case 0xd8:
 			/* SOI */
 			break;
+		case 0xd9:
+			/* EOI */
+			exit(0);
 		case 0xc4:
 			/* DHT (define Huffman tables) */
 			read_huffman_tables(&tables, byte_source_input_func, &source);