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