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