Line data Source code
1 : /*
2 : * jcmainct.c
3 : *
4 : * This file was part of the Independent JPEG Group's software:
5 : * Copyright (C) 1994-1996, Thomas G. Lane.
6 : * It was modified by The libjpeg-turbo Project to include only code relevant
7 : * to libjpeg-turbo.
8 : * For conditions of distribution and use, see the accompanying README.ijg
9 : * file.
10 : *
11 : * This file contains the main buffer controller for compression.
12 : * The main buffer lies between the pre-processor and the JPEG
13 : * compressor proper; it holds downsampled data in the JPEG colorspace.
14 : */
15 :
16 : #define JPEG_INTERNALS
17 : #include "jinclude.h"
18 : #include "jpeglib.h"
19 :
20 :
21 : /* Private buffer controller object */
22 :
23 : typedef struct {
24 : struct jpeg_c_main_controller pub; /* public fields */
25 :
26 : JDIMENSION cur_iMCU_row; /* number of current iMCU row */
27 : JDIMENSION rowgroup_ctr; /* counts row groups received in iMCU row */
28 : boolean suspended; /* remember if we suspended output */
29 : J_BUF_MODE pass_mode; /* current operating mode */
30 :
31 : /* If using just a strip buffer, this points to the entire set of buffers
32 : * (we allocate one for each component). In the full-image case, this
33 : * points to the currently accessible strips of the virtual arrays.
34 : */
35 : JSAMPARRAY buffer[MAX_COMPONENTS];
36 : } my_main_controller;
37 :
38 : typedef my_main_controller *my_main_ptr;
39 :
40 :
41 : /* Forward declarations */
42 : METHODDEF(void) process_data_simple_main
43 : (j_compress_ptr cinfo, JSAMPARRAY input_buf, JDIMENSION *in_row_ctr,
44 : JDIMENSION in_rows_avail);
45 :
46 :
47 : /*
48 : * Initialize for a processing pass.
49 : */
50 :
51 : METHODDEF(void)
52 0 : start_pass_main (j_compress_ptr cinfo, J_BUF_MODE pass_mode)
53 : {
54 0 : my_main_ptr main_ptr = (my_main_ptr) cinfo->main;
55 :
56 : /* Do nothing in raw-data mode. */
57 0 : if (cinfo->raw_data_in)
58 0 : return;
59 :
60 0 : if (pass_mode != JBUF_PASS_THRU)
61 0 : ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
62 :
63 0 : main_ptr->cur_iMCU_row = 0; /* initialize counters */
64 0 : main_ptr->rowgroup_ctr = 0;
65 0 : main_ptr->suspended = FALSE;
66 0 : main_ptr->pass_mode = pass_mode; /* save mode for use by process_data */
67 0 : main_ptr->pub.process_data = process_data_simple_main;
68 : }
69 :
70 :
71 : /*
72 : * Process some data.
73 : * This routine handles the simple pass-through mode,
74 : * where we have only a strip buffer.
75 : */
76 :
77 : METHODDEF(void)
78 0 : process_data_simple_main (j_compress_ptr cinfo,
79 : JSAMPARRAY input_buf, JDIMENSION *in_row_ctr,
80 : JDIMENSION in_rows_avail)
81 : {
82 0 : my_main_ptr main_ptr = (my_main_ptr) cinfo->main;
83 :
84 0 : while (main_ptr->cur_iMCU_row < cinfo->total_iMCU_rows) {
85 : /* Read input data if we haven't filled the main buffer yet */
86 0 : if (main_ptr->rowgroup_ctr < DCTSIZE)
87 0 : (*cinfo->prep->pre_process_data) (cinfo,
88 : input_buf, in_row_ctr, in_rows_avail,
89 0 : main_ptr->buffer, &main_ptr->rowgroup_ctr,
90 : (JDIMENSION) DCTSIZE);
91 :
92 : /* If we don't have a full iMCU row buffered, return to application for
93 : * more data. Note that preprocessor will always pad to fill the iMCU row
94 : * at the bottom of the image.
95 : */
96 0 : if (main_ptr->rowgroup_ctr != DCTSIZE)
97 0 : return;
98 :
99 : /* Send the completed row to the compressor */
100 0 : if (! (*cinfo->coef->compress_data) (cinfo, main_ptr->buffer)) {
101 : /* If compressor did not consume the whole row, then we must need to
102 : * suspend processing and return to the application. In this situation
103 : * we pretend we didn't yet consume the last input row; otherwise, if
104 : * it happened to be the last row of the image, the application would
105 : * think we were done.
106 : */
107 0 : if (! main_ptr->suspended) {
108 0 : (*in_row_ctr)--;
109 0 : main_ptr->suspended = TRUE;
110 : }
111 0 : return;
112 : }
113 : /* We did finish the row. Undo our little suspension hack if a previous
114 : * call suspended; then mark the main buffer empty.
115 : */
116 0 : if (main_ptr->suspended) {
117 0 : (*in_row_ctr)++;
118 0 : main_ptr->suspended = FALSE;
119 : }
120 0 : main_ptr->rowgroup_ctr = 0;
121 0 : main_ptr->cur_iMCU_row++;
122 : }
123 : }
124 :
125 :
126 : /*
127 : * Initialize main buffer controller.
128 : */
129 :
130 : GLOBAL(void)
131 0 : jinit_c_main_controller (j_compress_ptr cinfo, boolean need_full_buffer)
132 : {
133 : my_main_ptr main_ptr;
134 : int ci;
135 : jpeg_component_info *compptr;
136 :
137 0 : main_ptr = (my_main_ptr)
138 0 : (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
139 : sizeof(my_main_controller));
140 0 : cinfo->main = (struct jpeg_c_main_controller *) main_ptr;
141 0 : main_ptr->pub.start_pass = start_pass_main;
142 :
143 : /* We don't need to create a buffer in raw-data mode. */
144 0 : if (cinfo->raw_data_in)
145 0 : return;
146 :
147 : /* Create the buffer. It holds downsampled data, so each component
148 : * may be of a different size.
149 : */
150 0 : if (need_full_buffer) {
151 0 : ERREXIT(cinfo, JERR_BAD_BUFFER_MODE);
152 : } else {
153 : /* Allocate a strip buffer for each component */
154 0 : for (ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
155 0 : ci++, compptr++) {
156 0 : main_ptr->buffer[ci] = (*cinfo->mem->alloc_sarray)
157 : ((j_common_ptr) cinfo, JPOOL_IMAGE,
158 0 : compptr->width_in_blocks * DCTSIZE,
159 0 : (JDIMENSION) (compptr->v_samp_factor * DCTSIZE));
160 : }
161 : }
162 : }
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