diff options
Diffstat (limited to 'jidctfst.c')
| -rw-r--r-- | jidctfst.c | 31 |
1 files changed, 17 insertions, 14 deletions
@@ -1,9 +1,12 @@ /* * jidctfst.c * + * This file was part of the Independent JPEG Group's software: * Copyright (C) 1994-1998, Thomas G. Lane. - * This file is part of the Independent JPEG Group's software. - * For conditions of distribution and use, see the accompanying README file. + * libjpeg-turbo Modifications: + * Copyright (C) 2015, D. R. Commander. + * For conditions of distribution and use, see the accompanying README.ijg + * file. * * This file contains a fast, not so accurate integer implementation of the * inverse DCT (Discrete Cosine Transform). In the IJG code, this routine @@ -17,8 +20,8 @@ * This implementation is based on Arai, Agui, and Nakajima's algorithm for * scaled DCT. Their original paper (Trans. IEICE E-71(11):1095) is in * Japanese, but the algorithm is described in the Pennebaker & Mitchell - * JPEG textbook (see REFERENCES section in file README). The following code - * is based directly on figure 4-8 in P&M. + * JPEG textbook (see REFERENCES section in file README.ijg). The following + * code is based directly on figure 4-8 in P&M. * While an 8-point DCT cannot be done in less than 11 multiplies, it is * possible to arrange the computation so that many of the multiplies are * simple scalings of the final outputs. These multiplies can then be @@ -89,10 +92,10 @@ */ #if CONST_BITS == 8 -#define FIX_1_082392200 ((INT32) 277) /* FIX(1.082392200) */ -#define FIX_1_414213562 ((INT32) 362) /* FIX(1.414213562) */ -#define FIX_1_847759065 ((INT32) 473) /* FIX(1.847759065) */ -#define FIX_2_613125930 ((INT32) 669) /* FIX(2.613125930) */ +#define FIX_1_082392200 ((JLONG) 277) /* FIX(1.082392200) */ +#define FIX_1_414213562 ((JLONG) 362) /* FIX(1.414213562) */ +#define FIX_1_847759065 ((JLONG) 473) /* FIX(1.847759065) */ +#define FIX_2_613125930 ((JLONG) 669) /* FIX(2.613125930) */ #else #define FIX_1_082392200 FIX(1.082392200) #define FIX_1_414213562 FIX(1.414213562) @@ -112,7 +115,7 @@ #endif -/* Multiply a DCTELEM variable by an INT32 constant, and immediately +/* Multiply a DCTELEM variable by an JLONG constant, and immediately * descale to yield a DCTELEM result. */ @@ -122,7 +125,7 @@ /* Dequantize a coefficient by multiplying it by the multiplier-table * entry; produce a DCTELEM result. For 8-bit data a 16x16->16 * multiplication will do. For 12-bit data, the multiplier table is - * declared INT32, so a 32-bit multiply will be used. + * declared JLONG, so a 32-bit multiply will be used. */ #if BITS_IN_JSAMPLE == 8 @@ -134,7 +137,7 @@ /* Like DESCALE, but applies to a DCTELEM and produces an int. - * We assume that int right shift is unsigned if INT32 right shift is. + * We assume that int right shift is unsigned if JLONG right shift is. */ #ifdef RIGHT_SHIFT_IS_UNSIGNED @@ -165,7 +168,7 @@ */ GLOBAL(void) -jpeg_idct_ifast (j_decompress_ptr cinfo, jpeg_component_info * compptr, +jpeg_idct_ifast (j_decompress_ptr cinfo, jpeg_component_info *compptr, JCOEFPTR coef_block, JSAMPARRAY output_buf, JDIMENSION output_col) { @@ -173,8 +176,8 @@ jpeg_idct_ifast (j_decompress_ptr cinfo, jpeg_component_info * compptr, DCTELEM tmp10, tmp11, tmp12, tmp13; DCTELEM z5, z10, z11, z12, z13; JCOEFPTR inptr; - IFAST_MULT_TYPE * quantptr; - int * wsptr; + IFAST_MULT_TYPE *quantptr; + int *wsptr; JSAMPROW outptr; JSAMPLE *range_limit = IDCT_range_limit(cinfo); int ctr; |