| /* |

| * jchuff.h |

| * |

| * This file was part of the Independent JPEG Group's software: |

| * Copyright (C) 1991-1997, Thomas G. Lane. |

| * libjpeg-turbo Modifications: |

| * Copyright (C) 2022, D. R. Commander. |

| * For conditions of distribution and use, see the accompanying README.ijg |

| * file. |

| * |

| * This file contains declarations for Huffman entropy encoding routines |

| * that are shared between the sequential encoder (jchuff.c) and the |

| * progressive encoder (jcphuff.c). No other modules need to see these. |

| */ |

| |

| /* The legal range of a DCT coefficient is |

| * -1024 .. +1023 for 8-bit data; |

| * -16384 .. +16383 for 12-bit data. |

| * Hence the magnitude should always fit in 10 or 14 bits respectively. |

| */ |

| |

| /* The progressive Huffman encoder uses an unsigned 16-bit data type to store |

| * absolute values of coefficients, because it is possible to inject a |

| * coefficient value of -32768 into the encoder by attempting to transform a |

| * malformed 12-bit JPEG image, and the absolute value of -32768 would overflow |

| * a signed 16-bit integer. |

| */ |

| typedef unsigned short UJCOEF; |

| |

| /* Derived data constructed for each Huffman table */ |

| |

| typedef struct { |

| unsigned int ehufco[256]; /* code for each symbol */ |

| char ehufsi[256]; /* length of code for each symbol */ |

| /* If no code has been allocated for a symbol S, ehufsi[S] contains 0 */ |

| } c_derived_tbl; |

| |

| /* Expand a Huffman table definition into the derived format */ |

| EXTERN(void) jpeg_make_c_derived_tbl(j_compress_ptr cinfo, boolean isDC, |

| int tblno, c_derived_tbl **pdtbl); |

| |

| /* Generate an optimal table definition given the specified counts */ |

| EXTERN(void) jpeg_gen_optimal_table(j_compress_ptr cinfo, JHUFF_TBL *htbl, |

| long freq[]); |