4 * This file was part of the Independent JPEG Group's software:
5 * Copyright (C) 1994-1996, Thomas G. Lane.
6 * For conditions of distribution and use, see the accompanying README.ijg
10 #define JPEG_INTERNALS
15 /* Private buffer controller object */
18 struct jpeg_d_main_controller pub
; /* public fields */
20 /* Pointer to allocated workspace (M or M+2 row groups). */
21 JSAMPARRAY buffer
[MAX_COMPONENTS
];
23 boolean buffer_full
; /* Have we gotten an iMCU row from decoder? */
24 JDIMENSION rowgroup_ctr
; /* counts row groups output to postprocessor */
26 /* Remaining fields are only used in the context case. */
28 /* These are the master pointers to the funny-order pointer lists. */
29 JSAMPIMAGE xbuffer
[2]; /* pointers to weird pointer lists */
31 int whichptr
; /* indicates which pointer set is now in use */
32 int context_state
; /* process_data state machine status */
33 JDIMENSION rowgroups_avail
; /* row groups available to postprocessor */
34 JDIMENSION iMCU_row_ctr
; /* counts iMCU rows to detect image top/bot */
37 typedef my_main_controller
*my_main_ptr
;
40 /* context_state values: */
41 #define CTX_PREPARE_FOR_IMCU 0 /* need to prepare for MCU row */
42 #define CTX_PROCESS_IMCU 1 /* feeding iMCU to postprocessor */
43 #define CTX_POSTPONED_ROW 2 /* feeding postponed row group */
47 set_wraparound_pointers(j_decompress_ptr cinfo
)
48 /* Set up the "wraparound" pointers at top and bottom of the pointer lists.
49 * This changes the pointer list state from top-of-image to the normal state.
52 my_main_ptr main_ptr
= (my_main_ptr
)cinfo
->main
;
54 int M
= cinfo
->_min_DCT_scaled_size
;
55 jpeg_component_info
*compptr
;
56 JSAMPARRAY xbuf0
, xbuf1
;
58 for (ci
= 0, compptr
= cinfo
->comp_info
; ci
< cinfo
->num_components
;
60 rgroup
= (compptr
->v_samp_factor
* compptr
->_DCT_scaled_size
) /
61 cinfo
->_min_DCT_scaled_size
; /* height of a row group of component */
62 xbuf0
= main_ptr
->xbuffer
[0][ci
];
63 xbuf1
= main_ptr
->xbuffer
[1][ci
];
64 for (i
= 0; i
< rgroup
; i
++) {
65 xbuf0
[i
- rgroup
] = xbuf0
[rgroup
* (M
+ 1) + i
];
66 xbuf1
[i
- rgroup
] = xbuf1
[rgroup
* (M
+ 1) + i
];
67 xbuf0
[rgroup
* (M
+ 2) + i
] = xbuf0
[i
];
68 xbuf1
[rgroup
* (M
+ 2) + i
] = xbuf1
[i
];