static void msvideo1_decode_8bit(Msvideo1Context *s) { int block_ptr, pixel_ptr; int total_blocks; int pixel_x, pixel_y; /* pixel width and height iterators */ int block_x, block_y; /* block width and height iterators */ int blocks_wide, blocks_high; /* width and height in 4x4 blocks */ int block_inc; int row_dec; /* decoding parameters */ int stream_ptr; unsigned char byte_a, byte_b; unsigned short flags; int skip_blocks; unsigned char colors[8]; unsigned char *pixels = s->frame.data[0]; unsigned char *prev_pixels = s->prev_frame.data[0]; int stride = s->frame.linesize[0]; stream_ptr = 0; skip_blocks = 0; blocks_wide = s->avctx->width / 4; blocks_high = s->avctx->height / 4; total_blocks = blocks_wide * blocks_high; block_inc = 4; row_dec = stride + 4; for (block_y = blocks_high; block_y > 0; block_y--) { block_ptr = ((block_y * 4) - 1) * stride; for (block_x = blocks_wide; block_x > 0; block_x--) { /* check if this block should be skipped */ if (skip_blocks) { COPY_PREV_BLOCK(); block_ptr += block_inc; skip_blocks--; total_blocks--; continue; } pixel_ptr = block_ptr; /* get the next two bytes in the encoded data stream */ CHECK_STREAM_PTR(2); byte_a = s->buf[stream_ptr++]; byte_b = s->buf[stream_ptr++]; /* check if the decode is finished */ if ((byte_a == 0) && (byte_b == 0) && (total_blocks == 0)) return; else if ((byte_b & 0xFC) == 0x84) { /* skip code, but don't count the current block */ skip_blocks = ((byte_b - 0x84) << 8) + byte_a - 1; COPY_PREV_BLOCK(); } else if (byte_b < 0x80) { /* 2-color encoding */ flags = (byte_b << 8) | byte_a; CHECK_STREAM_PTR(2); colors[0] = s->buf[stream_ptr++]; colors[1] = s->buf[stream_ptr++]; for (pixel_y = 0; pixel_y < 4; pixel_y++) { for (pixel_x = 0; pixel_x < 4; pixel_x++, flags >>= 1) pixels[pixel_ptr++] = colors[(flags & 0x1) ^ 1]; pixel_ptr -= row_dec; } } else if (byte_b >= 0x90) { /* 8-color encoding */ flags = (byte_b << 8) | byte_a; CHECK_STREAM_PTR(8); memcpy(colors, &s->buf[stream_ptr], 8); stream_ptr += 8; for (pixel_y = 0; pixel_y < 4; pixel_y++) { for (pixel_x = 0; pixel_x < 4; pixel_x++, flags >>= 1) pixels[pixel_ptr++] = colors[((pixel_y & 0x2) << 1) + (pixel_x & 0x2) + ((flags & 0x1) ^ 1)]; pixel_ptr -= row_dec; } } else { /* 1-color encoding */ colors[0] = byte_a; for (pixel_y = 0; pixel_y < 4; pixel_y++) { for (pixel_x = 0; pixel_x < 4; pixel_x++) pixels[pixel_ptr++] = colors[0]; pixel_ptr -= row_dec; } } block_ptr += block_inc; total_blocks--; } } /* make the palette available on the way out */ if (s->avctx->pix_fmt == PIX_FMT_PAL8) memcpy(s->frame.data[1], s->palette, PALETTE_COUNT * 4); }