! HUF_readStats() : Read compact Huffman tree, saved by HUF_writeCTable(). `huffWeight` is destination buffer. `rankStats` is assumed to be a table of at least HUF_TABLELOG_MAX U32. @return : size read from `src` , or an error Code . Note : Needed by HUF_readCTable() and HUF_readDTableX?() . */
| 2630 | Note : Needed by HUF_readCTable() and HUF_readDTableX?() . |
| 2631 | */ |
| 2632 | size_t HUF_readStats(BYTE* huffWeight, size_t hwSize, U32* rankStats, |
| 2633 | U32* nbSymbolsPtr, U32* tableLogPtr, |
| 2634 | const void* src, size_t srcSize) |
| 2635 | { |
| 2636 | U32 weightTotal; |
| 2637 | const BYTE* ip = (const BYTE*) src; |
| 2638 | size_t iSize; |
| 2639 | size_t oSize; |
| 2640 | |
| 2641 | if (!srcSize) return ERROR(srcSize_wrong); |
| 2642 | iSize = ip[0]; |
| 2643 | /* memset(huffWeight, 0, hwSize); *//* is not necessary, even though some analyzer complain ... */ |
| 2644 | |
| 2645 | if (iSize >= 128) { /* special header */ |
| 2646 | oSize = iSize - 127; |
| 2647 | iSize = ((oSize+1)/2); |
| 2648 | if (iSize+1 > srcSize) return ERROR(srcSize_wrong); |
| 2649 | if (oSize >= hwSize) return ERROR(corruption_detected); |
| 2650 | ip += 1; |
| 2651 | { U32 n; |
| 2652 | for (n=0; n<oSize; n+=2) { |
| 2653 | huffWeight[n] = ip[n/2] >> 4; |
| 2654 | huffWeight[n+1] = ip[n/2] & 15; |
| 2655 | } } } |
| 2656 | else { /* header compressed with FSE (normal case) */ |
| 2657 | FSE_DTable fseWorkspace[FSE_DTABLE_SIZE_U32(6)]; /* 6 is max possible tableLog for HUF header (maybe even 5, to be tested) */ |
| 2658 | if (iSize+1 > srcSize) return ERROR(srcSize_wrong); |
| 2659 | oSize = FSE_decompress_wksp(huffWeight, hwSize-1, ip+1, iSize, fseWorkspace, 6); /* max (hwSize-1) values decoded, as last one is implied */ |
| 2660 | if (FSE_isError(oSize)) return oSize; |
| 2661 | } |
| 2662 | |
| 2663 | /* collect weight stats */ |
| 2664 | memset(rankStats, 0, (HUF_TABLELOG_MAX + 1) * sizeof(U32)); |
| 2665 | weightTotal = 0; |
| 2666 | { U32 n; for (n=0; n<oSize; n++) { |
| 2667 | if (huffWeight[n] >= HUF_TABLELOG_MAX) return ERROR(corruption_detected); |
| 2668 | rankStats[huffWeight[n]]++; |
| 2669 | weightTotal += (1 << huffWeight[n]) >> 1; |
| 2670 | } } |
| 2671 | if (weightTotal == 0) return ERROR(corruption_detected); |
| 2672 | |
| 2673 | /* get last non-null symbol weight (implied, total must be 2^n) */ |
| 2674 | { U32 const tableLog = BIT_highbit32(weightTotal) + 1; |
| 2675 | if (tableLog > HUF_TABLELOG_MAX) return ERROR(corruption_detected); |
| 2676 | *tableLogPtr = tableLog; |
| 2677 | /* determine last weight */ |
| 2678 | { U32 const total = 1 << tableLog; |
| 2679 | U32 const rest = total - weightTotal; |
| 2680 | U32 const verif = 1 << BIT_highbit32(rest); |
| 2681 | U32 const lastWeight = BIT_highbit32(rest) + 1; |
| 2682 | if (verif != rest) return ERROR(corruption_detected); /* last value must be a clean power of 2 */ |
| 2683 | huffWeight[oSize] = (BYTE)lastWeight; |
| 2684 | rankStats[lastWeight]++; |
| 2685 | } } |
| 2686 | |
| 2687 | /* check tree construction validity */ |
| 2688 | if ((rankStats[1] < 2) || (rankStats[1] & 1)) return ERROR(corruption_detected); /* by construction : at least 2 elts of rank 1, must be even */ |
| 2689 |
no test coverage detected