tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * Fast C2P (Chunky-to-Planar) Conversion
3 *
4 * Copyright (C) 2003 Geert Uytterhoeven
5 *
6 * NOTES:
7 * - This code was inspired by Scout's C2P tutorial
8 * - It assumes to run on a big endian system
9 *
10 * This file is subject to the terms and conditions of the GNU General Public
11 * License. See the file COPYING in the main directory of this archive
12 * for more details.
13 */
14
15#include <linux/module.h>
16#include <linux/string.h>
17#include "c2p.h"
18
19
20 /*
21 * Basic transpose step
22 */
23
24#define _transp(d, i1, i2, shift, mask) \
25 do { \
26 u32 t = (d[i1] ^ (d[i2] >> shift)) & mask; \
27 d[i1] ^= t; \
28 d[i2] ^= t << shift; \
29 } while (0)
30
31static inline u32 get_mask(int n)
32{
33 switch (n) {
34 case 1:
35 return 0x55555555;
36 break;
37
38 case 2:
39 return 0x33333333;
40 break;
41
42 case 4:
43 return 0x0f0f0f0f;
44 break;
45
46 case 8:
47 return 0x00ff00ff;
48 break;
49
50 case 16:
51 return 0x0000ffff;
52 break;
53 }
54 return 0;
55}
56
57#define transp_nx1(d, n) \
58 do { \
59 u32 mask = get_mask(n); \
60 /* First block */ \
61 _transp(d, 0, 1, n, mask); \
62 /* Second block */ \
63 _transp(d, 2, 3, n, mask); \
64 /* Third block */ \
65 _transp(d, 4, 5, n, mask); \
66 /* Fourth block */ \
67 _transp(d, 6, 7, n, mask); \
68 } while (0)
69
70#define transp_nx2(d, n) \
71 do { \
72 u32 mask = get_mask(n); \
73 /* First block */ \
74 _transp(d, 0, 2, n, mask); \
75 _transp(d, 1, 3, n, mask); \
76 /* Second block */ \
77 _transp(d, 4, 6, n, mask); \
78 _transp(d, 5, 7, n, mask); \
79 } while (0)
80
81#define transp_nx4(d, n) \
82 do { \
83 u32 mask = get_mask(n); \
84 _transp(d, 0, 4, n, mask); \
85 _transp(d, 1, 5, n, mask); \
86 _transp(d, 2, 6, n, mask); \
87 _transp(d, 3, 7, n, mask); \
88 } while (0)
89
90#define transp(d, n, m) transp_nx ## m(d, n)
91
92
93 /*
94 * Perform a full C2P step on 32 8-bit pixels, stored in 8 32-bit words
95 * containing
96 * - 32 8-bit chunky pixels on input
97 * - permuted planar data on output
98 */
99
100static void c2p_8bpp(u32 d[8])
101{
102 transp(d, 16, 4);
103 transp(d, 8, 2);
104 transp(d, 4, 1);
105 transp(d, 2, 4);
106 transp(d, 1, 2);
107}
108
109
110 /*
111 * Array containing the permution indices of the planar data after c2p
112 */
113
114static const int perm_c2p_8bpp[8] = { 7, 5, 3, 1, 6, 4, 2, 0 };
115
116
117 /*
118 * Compose two values, using a bitmask as decision value
119 * This is equivalent to (a & mask) | (b & ~mask)
120 */
121
122static inline unsigned long comp(unsigned long a, unsigned long b,
123 unsigned long mask)
124{
125 return ((a ^ b) & mask) ^ b;
126}
127
128
129 /*
130 * Store a full block of planar data after c2p conversion
131 */
132
133static inline void store_planar(char *dst, u32 dst_inc, u32 bpp, u32 d[8])
134{
135 int i;
136
137 for (i = 0; i < bpp; i++, dst += dst_inc)
138 *(u32 *)dst = d[perm_c2p_8bpp[i]];
139}
140
141
142 /*
143 * Store a partial block of planar data after c2p conversion
144 */
145
146static inline void store_planar_masked(char *dst, u32 dst_inc, u32 bpp,
147 u32 d[8], u32 mask)
148{
149 int i;
150
151 for (i = 0; i < bpp; i++, dst += dst_inc)
152 *(u32 *)dst = comp(d[perm_c2p_8bpp[i]], *(u32 *)dst, mask);
153}
154
155
156 /*
157 * c2p - Copy 8-bit chunky image data to a planar frame buffer
158 * @dst: Starting address of the planar frame buffer
159 * @dx: Horizontal destination offset (in pixels)
160 * @dy: Vertical destination offset (in pixels)
161 * @width: Image width (in pixels)
162 * @height: Image height (in pixels)
163 * @dst_nextline: Frame buffer offset to the next line (in bytes)
164 * @dst_nextplane: Frame buffer offset to the next plane (in bytes)
165 * @src_nextline: Image offset to the next line (in bytes)
166 * @bpp: Bits per pixel of the planar frame buffer (1-8)
167 */
168
169void c2p(u8 *dst, const u8 *src, u32 dx, u32 dy, u32 width, u32 height,
170 u32 dst_nextline, u32 dst_nextplane, u32 src_nextline, u32 bpp)
171{
172 int dst_idx;
173 u32 d[8], first, last, w;
174 const u8 *c;
175 u8 *p;
176
177 dst += dy*dst_nextline+(dx & ~31);
178 dst_idx = dx % 32;
179 first = ~0UL >> dst_idx;
180 last = ~(~0UL >> ((dst_idx+width) % 32));
181 while (height--) {
182 c = src;
183 p = dst;
184 w = width;
185 if (dst_idx+width <= 32) {
186 /* Single destination word */
187 first &= last;
188 memset(d, 0, sizeof(d));
189 memcpy((u8 *)d+dst_idx, c, width);
190 c += width;
191 c2p_8bpp(d);
192 store_planar_masked(p, dst_nextplane, bpp, d, first);
193 p += 4;
194 } else {
195 /* Multiple destination words */
196 w = width;
197 /* Leading bits */
198 if (dst_idx) {
199 w = 32 - dst_idx;
200 memset(d, 0, dst_idx);
201 memcpy((u8 *)d+dst_idx, c, w);
202 c += w;
203 c2p_8bpp(d);
204 store_planar_masked(p, dst_nextplane, bpp, d, first);
205 p += 4;
206 w = width-w;
207 }
208 /* Main chunk */
209 while (w >= 32) {
210 memcpy(d, c, 32);
211 c += 32;
212 c2p_8bpp(d);
213 store_planar(p, dst_nextplane, bpp, d);
214 p += 4;
215 w -= 32;
216 }
217 /* Trailing bits */
218 w %= 32;
219 if (w > 0) {
220 memcpy(d, c, w);
221 memset((u8 *)d+w, 0, 32-w);
222 c2p_8bpp(d);
223 store_planar_masked(p, dst_nextplane, bpp, d, last);
224 }
225 }
226 src += src_nextline;
227 dst += dst_nextline;
228 }
229}
230EXPORT_SYMBOL_GPL(c2p);
231
232MODULE_LICENSE("GPL");