summaryrefslogtreecommitdiffstats
path: root/firmware/target/coldfire/iriver/h300/lcd-as-h300.S
blob: 223c1838609ffe8e7aa6cb402beb2e55272b261c (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
/***************************************************************************
 *             __________               __   ___.
 *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
 *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
 *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
 *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
 *                     \/            \/     \/    \/            \/
 * $Id$
 *
 * Copyright (C) 2006 by Jens Arnold
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 ****************************************************************************/

#include "config.h"
#include "cpu.h"

    .section    .icode, "ax", @progbits

/* lcd_write_yuv420_lines()
 *
 * See http://en.wikipedia.org/wiki/YCbCr
 *   ITU-R BT.601 (formerly CCIR 601):
 *   |Y'|   | 0.299000  0.587000  0.114000| |R|
 *   |Pb| = |-0.168736 -0.331264  0.500000| |G| or 0.564334*(B - Y')
 *   |Pr|   | 0.500000 -0.418688  0.081312| |B| or 0.713267*(R - Y')
 *   Scaled, normalized and rounded:
 *   |Y'|   | 65  129   25| |R| +  16 : 16->235
 *   |Cb| = |-38  -74  112| |G| + 128 : 16->240
 *   |Cr|   |112  -94  -18| |B| + 128 : 16->240
 *
 *   The inverse:
 *   |R|   |1.000000  0.000000  1.402000| |Y'|
 *   |G| = |1.000000 -0.334136 -0.714136| |Pb|
 *   |B|   |1.000000  1.772000  0.000000| |Pr|
 *   Scaled, normalized, rounded and tweaked to yield RGB565:
 *   |R|   |19611723        0  26881894| |Y' -  16| >> 27
 *   |G| = |19611723 -6406711 -13692816| |Cb - 128| >> 26
 *   |B|   |19611723 33976259         0| |Cr - 128| >> 27
 *
 * Needs EMAC set to saturated, signed integer mode.
 *
 * register usage:
 *   %a0 - LCD data port
 *   %a1 - Y pointer
 *   %a2 - C pointer
 *   %a3 - C width
 *   %a4 - Y end address
 *   %a5 - Y factor
 *   %a6 - BU factor
 *   %d0 - scratch
 *   %d1 -     B, previous Y \ alternating
 *   %d2 - U / B, previous Y /
 *   %d3 - V / G
 *   %d4 - R / output pixel
 *   %d5 - GU factor
 *   %d6 - GV factor
 *   %d7 - RGB signed -> unsigned conversion mask
 */
    .align      2
    .global     lcd_write_yuv420_lines
    .type       lcd_write_yuv420_lines, @function

lcd_write_yuv420_lines:
    lea.l   (-44, %sp), %sp         /* free up some registers */
    movem.l %d2-%d7/%a2-%a6, (%sp)
    
    lea.l   0xf0000002, %a0         /* LCD data port */
    movem.l (44+4, %sp), %a1-%a3    /* Y data, C data, C width */
    lea.l   (%a1, %a3*2), %a4       /* Y end address */

    move.l  #19611723, %a5          /* y factor */
    move.l  #33976259, %a6          /* bu factor */
    move.l  #-6406711, %d5          /* gu factor */
    move.l  #-13692816, %d6         /* gv factor */
    move.l  #0x8410, %d7            /* bitmask for signed->unsigned conversion
                                     * of R, G and B within RGB565 at once */

    /* chroma for first 2x2 pixel block */
    clr.l   %d3                     /* load v component */
    move.b  (%a2, %a3), %d3
    clr.l   %d2                     /* load u component */
    move.b  (%a2)+, %d2
    moveq.l #-128, %d0
    add.l   %d0, %d2
    add.l   %d0, %d3

    mac.l   %a6, %d2, %acc0         /* bu */
    mac.l   %d5, %d2, %acc1         /* gu */
    mac.l   %d6, %d3, %acc1         /* gv */
    move.l  #26881894, %d0          /* rv factor */
    mac.l   %d0, %d3, %acc2         /* rv */

    /* luma for very first pixel (top left) */
    clr.l   %d1
    move.b  (%a1, %a3*2), %d1
    moveq.l #-126, %d0
    add.l   %d1, %d0                /* y' (-0.5 ... +0.5) */
    mac.l   %a5, %d0, %acc0
    mac.l   %a5, %d0, %acc1
    mac.l   %a5, %d0, %acc2

    bra.b   .yuv_line_entry

.yuv_line_loop:
    /* chroma for 2x2 pixel block */
    clr.l   %d3                     /* load v component */
    move.b  (%a2, %a3), %d3
    clr.l   %d2                     /* load u component */
    move.b  (%a2)+, %d2
    moveq.l #-128, %d0
    add.l   %d0, %d2
    add.l   %d0, %d3

    mac.l   %a6, %d2, %acc0         /* bu */
    mac.l   %d5, %d2, %acc1         /* gu */
    mac.l   %d6, %d3, %acc1         /* gv */
    move.l  #26881894, %d0          /* rv factor */
    mac.l   %d0, %d3, %acc2         /* rv */

    /* luma for first pixel (top left) */
    clr.l   %d1
    move.b  (%a1, %a3*2), %d1
    moveq.l #-126, %d0
    add.l   %d1, %d0                /* y' (-0.5 ... +0.5) */
    mac.l   %a5, %d0, %acc0
    mac.l   %a5, %d0, %acc1
    mac.l   %a5, %d0, %acc2

    move.w  %d4, (%a0)
    /* LCD write is delayed one pixel to use it for filling the EMAC latency */

    /* convert to RGB565, pack and output */
.yuv_line_entry:
    moveq.l #27, %d0
    move.l  %acc0, %d2
    move.l  %acc1, %d3
    move.l  %acc2, %d4
    lsr.l   %d0, %d2
    lsr.l   %d0, %d4
    moveq.l #26, %d0
    lsr.l   %d0, %d3
    lsl.l   #6, %d4
    or.l    %d3, %d4
    lsl.l   #5, %d4
    or.l    %d2, %d4
    eor.l   %d7, %d4

    /* luma for second pixel (bottom left) as delta from the first */
    clr.l   %d2
    move.b  (%a1)+, %d2
    move.l  %d2, %d0
    sub.l   %d1, %d0
    mac.l   %a5, %d0, %acc0
    mac.l   %a5, %d0, %acc1
    mac.l   %a5, %d0, %acc2

    move.w  %d4, (%a0)
    /* LCD write is delayed one pixel to use it for filling the EMAC latency */

    /* convert to RGB565, pack and output */
    moveq.l #27, %d0
    move.l  %acc0, %d1
    move.l  %acc1, %d3
    move.l  %acc2, %d4
    lsr.l   %d0, %d1
    lsr.l   %d0, %d4
    moveq.l #26, %d0
    lsr.l   %d0, %d3
    lsl.l   #6, %d4
    or.l    %d3, %d4
    lsl.l   #5, %d4
    or.l    %d1, %d4
    eor.l   %d7, %d4

    /* luma for third pixel (top right) as delta from the second */
    clr.l   %d1
    move.b  (%a1, %a3*2), %d1
    move.l  %d1, %d0
    sub.l   %d2, %d0
    mac.l   %a5, %d0, %acc0
    mac.l   %a5, %d0, %acc1
    mac.l   %a5, %d0, %acc2

    move.w  %d4, (%a0)
    /* LCD write is delayed one pixel to use it for filling the EMAC latency */

    /* convert to RGB565, pack and output */
    moveq.l #27, %d0
    move.l  %acc0, %d2
    move.l  %acc1, %d3
    move.l  %acc2, %d4
    lsr.l   %d0, %d2
    lsr.l   %d0, %d4
    moveq.l #26, %d0
    lsr.l   %d0, %d3
    lsl.l   #6, %d4
    or.l    %d3, %d4
    lsl.l   #5, %d4
    or.l    %d2, %d4
    eor.l   %d7, %d4

    /* luma for fourth pixel (bottom right) as delta from the third */
    clr.l   %d2
    move.b  (%a1)+, %d2
    move.l  %d2, %d0
    sub.l   %d1, %d0
    mac.l   %a5, %d0, %acc0
    mac.l   %a5, %d0, %acc1
    mac.l   %a5, %d0, %acc2

    move.w  %d4, (%a0)
    /* LCD write is delayed one pixel to use it for filling the EMAC latency */

    /* convert to RGB565, pack and output */
    moveq.l #27, %d0
    movclr.l %acc0, %d1
    movclr.l %acc1, %d3
    movclr.l %acc2, %d4
    lsr.l   %d0, %d1
    lsr.l   %d0, %d4
    moveq.l #26, %d0
    lsr.l   %d0, %d3
    lsl.l   #6, %d4
    or.l    %d3, %d4
    lsl.l   #5, %d4
    or.l    %d1, %d4
    eor.l   %d7, %d4

    cmp.l   %a1, %a4                /* run %a1 up to end of line */
    bhi.w   .yuv_line_loop

    move.w  %d4, (%a0)              /* write (very) last pixel */

    movem.l (%sp), %d2-%d7/%a2-%a6
    lea.l   (44, %sp), %sp          /* restore registers */
    rts
.yuv_end:
    .size   lcd_write_yuv420_lines, .yuv_end - lcd_write_yuv420_lines