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)
assert(len >= 8);
image->precision = read_uint8(byte_source_input_func, source);
assert(image->precision == 8);
- image->width = read_uint16(byte_source_input_func, source);
image->height = read_uint16(byte_source_input_func, source);
+ image->width = read_uint16(byte_source_input_func, source);
image->num_components = read_uint8(byte_source_input_func, source);
len -= 8;
image->qtable[c] = read_uint8(byte_source_input_func, source);
len -= 3;
+ if (image->hsample[c] > image->max_hsample) {
+ image->max_hsample = image->hsample[c];
+ }
+ if (image->vsample[c] > image->max_vsample) {
+ image->max_vsample = image->vsample[c];
+ }
+
fprintf(stderr, "Component %u: sampling factors %u x %x, quantization table %u\n",
c, image->hsample[c], image->vsample[c], image->qtable[c]);
}
+
+ image->num_blocks_horizontal = (image->width + image->max_hsample * DCTSIZE - 1) / (image->max_hsample * DCTSIZE);
+ image->num_blocks_vertical = (image->height + image->max_vsample * DCTSIZE - 1) / (image->max_vsample * DCTSIZE);
+
+ for (unsigned c = 0; c < 256; ++c) {
+ if (image->hsample[c] == 0) {
+ continue;
+ }
+
+ 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)
+{
+ for (unsigned i = 1; i < DCTSIZE2; ++i) {
+ possibly_refill(bits, DEHUF_AC_TABLE_BITS);
+ unsigned lookup = peek_bits(bits, DEHUF_AC_TABLE_BITS);
+ int code = tbl->ac_table_codes[lookup];
+
+ if (__builtin_expect(code == AC_DEHUF_SLOW_PATH, 0)) {
+ 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;
+ }
+
+ coeff[unzigzag[i]] = extend(read_bits(bits, s), s);
+ } else {
+ unsigned 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;
+ }
+ coeff[unzigzag[i]] = code;
+ }
+ }
}
void read_scan(struct byte_source* source, struct jpeg_image* image, huffman_tables_t* tables)
}
struct bit_source bits;
- init_bit_source(&bits, byte_source_input_func, source);
+ init_bit_source(&bits, byte_source_input_func, 8, source);
- // Some debugging code.
- assert(image->width % 8 == 0);
- int y_stride = image->width;
- uint8_t* y_row_data = (uint8_t*)malloc(y_stride * DCTSIZE * image->vsample[1]);
- assert(y_row_data != NULL);
- int xb = 0;
+ 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];
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]]);
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;
- }
-
- possibly_refill(&bits, s);
-
- i += r;
- coeff[unzigzag[i]] = extend(read_bits(&bits, s), s);
- }
-
uint8_t pixdata[DCTSIZE2];
idct_choice(coeff, image->idct_data[image->qtable[cn]], pixdata);
- if (cn != 1) {
- continue;
- }
-
- for (int y = 0; y < DCTSIZE; ++y) {
- memcpy(y_row_data + (local_yb * DCTSIZE + y) * y_stride + (xb + local_xb) * DCTSIZE,
- 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);
}
}
}
-
- if (cn != 1) {
- continue;
+ 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];
}
- xb += image->hsample[cn];
- if (xb * DCTSIZE == y_stride) {
- fwrite(y_row_data, y_stride * DCTSIZE * image->vsample[cn], 1, stdout);
- xb = 0;
+ // 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);
}
}
}
case 0xd8:
/* SOI */
break;
+ case 0xd9:
+ /* EOI */
+ exit(0);
case 0xc4:
/* DHT (define Huffman tables) */
read_huffman_tables(&tables, byte_source_input_func, &source);
projects / fjl / blobdiff