Decode data block without bit accumulation
| FwStatus | fwiDecodeHuffman8x8_Direct_JPEG_1u16s_C1 | ( | const Fw8u * pSrc, int * pSrcBitsLen, Fw16s * pDst, Fw16s * pLastDC, int * pMarker, Fw32u * pPrefetchedBits, int * pNumValidPrefetchedBits, const FwiDecodeHuffmanSpec * pDcTable, const FwiDecodeHuffmanSpec * pAcTable ); |
| pAcTable | Pointer to the Huffman AC coefficient table. | |
| pDcTable | Pointer to the Huffman DC coefficient table. | |
| pDst | Pointer to a location in a destination buffer. | |
| pLastDC | Pointer to the last DC coefficient, which is in the previous 8X8 block. | |
| pMarker | Pointer to the JPEG marker position. | |
| pNumValidPrefetchedBits | Pointer to the value of valid bits in the prefetched buffer. | |
| pPrefetchedBits | Pointer to the prefetched buffer, which contains decoded data from the previous block. | |
| pSrc | Pointer to a location in a source buffer. | |
| pSrcBitsLen | Pointer to the source buffer length in bits. |
This function performs direct decoding of an 8X8 data block of Huffman-encoded quantized DC and AC DCT coefficients.
The decoding process follows CCITT Rec. T.81, Annex F.2.2.
The function writes only full bytes to the destination buffer. Incomplete bits from data blocks are not accumulated in the Huffman decode state structure.
When the function detects a JPEG marker, it stops decoding and writes the marker to the location specified by pMarker.
During function initialization, make sure that pLastDC, pMarker, and pNumValidPrefetchedBits are cleared to all zeroes.
After each restart interval, make sure that pLastDC and pNumValidPrefetchedBits are cleared to all zeroes.
After each found marker has been processed, make sure that pMarker and pNumValidPrefetchedBits are cleared to all zeroes.