jdcoefct.h (2873B)
1 /* 2 * jdcoefct.h 3 * 4 * This file was part of the Independent JPEG Group's software: 5 * Copyright (C) 1994-1997, Thomas G. Lane. 6 * libjpeg-turbo Modifications: 7 * Copyright 2009 Pierre Ossman <ossman@cendio.se> for Cendio AB 8 * Copyright (C) 2020, Google, Inc. 9 * Copyright (C) 2022, D. R. Commander. 10 * For conditions of distribution and use, see the accompanying README.ijg 11 * file. 12 */ 13 14 #define JPEG_INTERNALS 15 #include "jpeglib.h" 16 17 18 #if BITS_IN_JSAMPLE != 16 || defined(D_LOSSLESS_SUPPORTED) 19 20 /* Block smoothing is only applicable for progressive JPEG, so: */ 21 #ifndef D_PROGRESSIVE_SUPPORTED 22 #undef BLOCK_SMOOTHING_SUPPORTED 23 #endif 24 25 26 /* Private buffer controller object */ 27 28 typedef struct { 29 struct jpeg_d_coef_controller pub; /* public fields */ 30 31 /* These variables keep track of the current location of the input side. */ 32 /* cinfo->input_iMCU_row is also used for this. */ 33 JDIMENSION MCU_ctr; /* counts MCUs processed in current row */ 34 int MCU_vert_offset; /* counts MCU rows within iMCU row */ 35 int MCU_rows_per_iMCU_row; /* number of such rows needed */ 36 37 /* The output side's location is represented by cinfo->output_iMCU_row. */ 38 39 /* In single-pass modes, it's sufficient to buffer just one MCU. 40 * We allocate a workspace of D_MAX_BLOCKS_IN_MCU coefficient blocks, 41 * and let the entropy decoder write into that workspace each time. 42 * In multi-pass modes, this array points to the current MCU's blocks 43 * within the virtual arrays; it is used only by the input side. 44 */ 45 JBLOCKROW MCU_buffer[D_MAX_BLOCKS_IN_MCU]; 46 47 /* Temporary workspace for one MCU */ 48 JCOEF *workspace; 49 50 #ifdef D_MULTISCAN_FILES_SUPPORTED 51 /* In multi-pass modes, we need a virtual block array for each component. */ 52 jvirt_barray_ptr whole_image[MAX_COMPONENTS]; 53 #endif 54 55 #ifdef BLOCK_SMOOTHING_SUPPORTED 56 /* When doing block smoothing, we latch coefficient Al values here */ 57 int *coef_bits_latch; 58 #define SAVED_COEFS 10 /* we save coef_bits[0..9] */ 59 #endif 60 } my_coef_controller; 61 62 typedef my_coef_controller *my_coef_ptr; 63 64 65 LOCAL(void) 66 start_iMCU_row(j_decompress_ptr cinfo) 67 /* Reset within-iMCU-row counters for a new row (input side) */ 68 { 69 my_coef_ptr coef = (my_coef_ptr)cinfo->coef; 70 71 /* In an interleaved scan, an MCU row is the same as an iMCU row. 72 * In a noninterleaved scan, an iMCU row has v_samp_factor MCU rows. 73 * But at the bottom of the image, process only what's left. 74 */ 75 if (cinfo->comps_in_scan > 1) { 76 coef->MCU_rows_per_iMCU_row = 1; 77 } else { 78 if (cinfo->input_iMCU_row < (cinfo->total_iMCU_rows - 1)) 79 coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->v_samp_factor; 80 else 81 coef->MCU_rows_per_iMCU_row = cinfo->cur_comp_info[0]->last_row_height; 82 } 83 84 coef->MCU_ctr = 0; 85 coef->MCU_vert_offset = 0; 86 } 87 88 #endif /* BITS_IN_JSAMPLE != 16 || defined(D_LOSSLESS_SUPPORTED) */