SDL_stretch.c
1
2
/*
SDL - Simple DirectMedia Layer
3
Copyright (C) 1997-2006 Sam Lantinga
4
5
This library is free software; you can redistribute it and/or
6
modify it under the terms of the GNU Lesser General Public
7
License as published by the Free Software Foundation; either
8
version 2.1 of the License, or (at your option) any later version.
9
10
11
12
This library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13
Lesser General Public License for more details.
15
16
17
You should have received a copy of the GNU Lesser General Public
License along with this library; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
18
19
Sam Lantinga
20
slouken@libsdl.org
21
*/
22
#include "SDL_config.h"
23
24
25
26
27
28
29
30
31
32
33
34
35
36
/* This a stretch blit implementation based on ideas given to me by
Tomasz Cejner - thanks! :)
April 27, 2000 - Sam Lantinga
*/
#include "SDL_video.h"
#include "SDL_blit.h"
/* This isn't ready for general consumption yet - it should be folded
into the general blitting mechanism.
*/
37
#if ((defined(_MFC_VER) && defined(_M_IX86)/* && !defined(_WIN32_WCE) still needed? */) || \
38
(defined(__GNUC__) && defined(__i386__))) && SDL_ASSEMBLY_ROUTINES
39
40
41
42
43
#define USE_ASM_STRETCH
#endif
#ifdef USE_ASM_STRETCH
44
#if defined(_M_IX86) || defined(i386)
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
#define PREFIX16 0x66
#define STORE_BYTE 0xAA
#define STORE_WORD 0xAB
#define LOAD_BYTE 0xAC
#define LOAD_WORD 0xAD
#define RETURN 0xC3
#else
#error Need assembly opcodes for this architecture
#endif
static unsigned char copy_row[4096];
static int generate_rowbytes(int src_w, int dst_w, int bpp)
{
static struct {
int bpp;
int src_w;
int dst_w;
} last;
int i;
int pos, inc;
unsigned char *eip;
unsigned char load, store;
/* See if we need to regenerate the copy buffer */
if ( (src_w == last.src_w) &&
72
(dst_w == last.dst_w) && (bpp == last.bpp) ) {
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
return(0);
}
last.bpp = bpp;
last.src_w = src_w;
last.dst_w = dst_w;
switch (bpp) {
case 1:
load = LOAD_BYTE;
store = STORE_BYTE;
break;
case 2:
case 4:
load = LOAD_WORD;
store = STORE_WORD;
break;
default:
SDL_SetError("ASM stretch of %d bytes isn't supported\n", bpp);
return(-1);
}
pos = 0x10000;
inc = (src_w << 16) / dst_w;
eip = copy_row;
for ( i=0; i<dst_w; ++i ) {
while ( pos >= 0x10000L ) {
if ( bpp == 2 ) {
*eip++ = PREFIX16;
}
*eip++ = load;
pos -= 0x10000L;
}
if ( bpp == 2 ) {
*eip++ = PREFIX16;
}
*eip++ = store;
pos += inc;
}
*eip++ = RETURN;
/* Verify that we didn't overflow (too late) */
if ( eip > (copy_row+sizeof(copy_row)) ) {
SDL_SetError("Copy buffer overflow");
return(-1);
}
return(0);
}
#else
#define DEFINE_COPY_ROW(name, type) \
void name(type *src, int src_w, type *dst, int dst_w) \
{ \
int i; \
int pos, inc; \
type pixel = 0; \
\
pos = 0x10000; \
inc = (src_w << 16) / dst_w; \
for ( i=dst_w; i>0; --i ) { \
while ( pos >= 0x10000L ) { \
pixel = *src++; \
pos -= 0x10000L; \
} \
*dst++ = pixel; \
pos += inc; \
} \
}
DEFINE_COPY_ROW(copy_row1, Uint8)
DEFINE_COPY_ROW(copy_row2, Uint16)
DEFINE_COPY_ROW(copy_row4, Uint32)
#endif /* USE_ASM_STRETCH */
/* The ASM code doesn't handle 24-bpp stretch blits */
void copy_row3(Uint8 *src, int src_w, Uint8 *dst, int dst_w)
{
int i;
int pos, inc;
Uint8 pixel[3];
pos = 0x10000;
inc = (src_w << 16) / dst_w;
for ( i=dst_w; i>0; --i ) {
while ( pos >= 0x10000L ) {
pixel[0] = *src++;
pixel[1] = *src++;
pixel[2] = *src++;
pos -= 0x10000L;
}
*dst++ = pixel[0];
*dst++ = pixel[1];
*dst++ = pixel[2];
pos += inc;
}
}
/* Perform a stretch blit between two surfaces of the same format.
NOTE: This function is not safe to call from multiple threads!
*/
int SDL_SoftStretch(SDL_Surface *src, SDL_Rect *srcrect,
SDL_Surface *dst, SDL_Rect *dstrect)
{
175
176
int src_locked;
int dst_locked;
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
int pos, inc;
int dst_width;
int dst_maxrow;
int src_row, dst_row;
Uint8 *srcp = NULL;
Uint8 *dstp;
SDL_Rect full_src;
SDL_Rect full_dst;
#if defined(USE_ASM_STRETCH) && defined(__GNUC__)
int u1, u2;
#endif
const int bpp = dst->format->BytesPerPixel;
if ( src->format->BitsPerPixel != dst->format->BitsPerPixel ) {
SDL_SetError("Only works with same format surfaces");
return(-1);
}
/* Verify the blit rectangles */
if ( srcrect ) {
if ( (srcrect->x < 0) || (srcrect->y < 0) ||
((srcrect->x+srcrect->w) > src->w) ||
((srcrect->y+srcrect->h) > src->h) ) {
SDL_SetError("Invalid source blit rectangle");
return(-1);
}
} else {
full_src.x = 0;
full_src.y = 0;
full_src.w = src->w;
full_src.h = src->h;
srcrect = &full_src;
}
if ( dstrect ) {
if ( (dstrect->x < 0) || (dstrect->y < 0) ||
((dstrect->x+dstrect->w) > dst->w) ||
((dstrect->y+dstrect->h) > dst->h) ) {
SDL_SetError("Invalid destination blit rectangle");
return(-1);
}
} else {
full_dst.x = 0;
full_dst.y = 0;
full_dst.w = dst->w;
full_dst.h = dst->h;
dstrect = &full_dst;
}
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
/* Lock the destination if it's in hardware */
dst_locked = 0;
if ( SDL_MUSTLOCK(dst) ) {
if ( SDL_LockSurface(dst) < 0 ) {
SDL_SetError("Unable to lock destination surface");
return(-1);
}
dst_locked = 1;
}
/* Lock the source if it's in hardware */
src_locked = 0;
if ( SDL_MUSTLOCK(src) ) {
if ( SDL_LockSurface(src) < 0 ) {
if ( dst_locked ) {
SDL_UnlockSurface(dst);
}
SDL_SetError("Unable to lock source surface");
return(-1);
}
src_locked = 1;
}
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
/* Set up the data... */
pos = 0x10000;
inc = (srcrect->h << 16) / dstrect->h;
src_row = srcrect->y;
dst_row = dstrect->y;
dst_width = dstrect->w*bpp;
#ifdef USE_ASM_STRETCH
/* Write the opcodes for this stretch */
if ( (bpp != 3) &&
(generate_rowbytes(srcrect->w, dstrect->w, bpp) < 0) ) {
return(-1);
}
#endif
/* Perform the stretch blit */
for ( dst_maxrow = dst_row+dstrect->h; dst_row<dst_maxrow; ++dst_row ) {
dstp = (Uint8 *)dst->pixels + (dst_row*dst->pitch)
+ (dstrect->x*bpp);
while ( pos >= 0x10000L ) {
srcp = (Uint8 *)src->pixels + (src_row*src->pitch)
+ (srcrect->x*bpp);
++src_row;
pos -= 0x10000L;
}
#ifdef USE_ASM_STRETCH
switch (bpp) {
case 3:
copy_row3(srcp, srcrect->w, dstp, dstrect->w);
break;
default:
#ifdef __GNUC__
279
__asm__ __volatile__ (
280
"call *%4"
281
: "=&D" (u1), "=&S" (u2)
282
: "0" (dstp), "1" (srcp), "r" (copy_row)
283
284
: "memory" );
#else
285
#ifdef _MSC_VER
286
{ void *code = copy_row;
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
__asm {
push edi
push esi
mov edi, dstp
mov esi, srcp
call dword ptr code
pop esi
pop edi
}
}
#else
#error Need inline assembly for this compiler
#endif
#endif /* __GNUC__ */
break;
}
#else
switch (bpp) {
case 1:
copy_row1(srcp, srcrect->w, dstp, dstrect->w);
break;
case 2:
copy_row2((Uint16 *)srcp, srcrect->w,
(Uint16 *)dstp, dstrect->w);
break;
case 3:
copy_row3(srcp, srcrect->w, dstp, dstrect->w);
break;
case 4:
copy_row4((Uint32 *)srcp, srcrect->w,
(Uint32 *)dstp, dstrect->w);
break;
}
#endif
pos += inc;
}
325
326
327
328
329
330
331
332
/* We need to unlock the surfaces if they're locked */
if ( dst_locked ) {
SDL_UnlockSurface(dst);
}
if ( src_locked ) {
SDL_UnlockSurface(src);
}
333
334
return(0);
}