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| 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 * For conditions of distribution and use, see the accompanying README file. |
| 9 */ |
| 10 |
| 11 #define JPEG_INTERNALS |
| 12 #include "jinclude.h" |
| 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 } |
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