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@ ScummVM Scumm Interpreter
@ Copyright (C) 2007 The ScummVM project
@
@ 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 program 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 General Public License for more details.
@
@ You should have received a copy of the GNU General Public License
@ along with this program@ if not, write to the Free Software
@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
@
@ $URL: $
@ $Id: $
@
@ @author Robin Watts (robin@wss.co.uk)
.text
.global asmDrawStripToScreen
@ ARM implementation of asmDrawStripToScreen.
@
@ C prototype would be:
@
@ extern "C" void asmDrawStripToScreen(int height,
@ int width,
@ byte const *text,
@ byte const *src,
@ byte *dst,
@ int vsPitch,
@ int vsScreenWidth,
@ int textSurfacePitch);
@
@ In addition, we assume that text, src and dst are all word (4 byte)
@ aligned. This is the same assumption that the old 'inline' version
@ made.
asmDrawStripToScreen:
@ r0 = height
@ r1 = width
@ r2 = text
@ r3 = src
MOV r12,r13
STMFD r13!,{r4-r7,r9-r11,R14}
LDMIA r12,{r4,r5,r6,r7}
@ r4 = dst
@ r5 = vsPitch
@ r6 = vmScreenWidth
@ r7 = textSurfacePitch
CMP r0,#0 @ If height<=0
MOVLE r0,#1 @ height=1
CMP r1,#4 @ If width<4
BLT end @ return
@ Width &= ~4 ? What's that about then? Width &= ~3 I could have
@ understood...
BIC r1,r1,#4
SUB r5,r5,r1 @ vsPitch -= width
SUB r6,r6,r1 @ vmScreenWidth -= width
SUB r7,r7,r1 @ textSurfacePitch -= width
MOV r10,#253
ORR r10,r10,r10,LSL #8
ORR r10,r10,r10,LSL #16 @ r10 = mask
yLoop:
MOV r14,r1 @ r14 = width
xLoop:
LDR r12,[r2],#4 @ r12 = [text]
LDR r11,[r3],#4 @ r11 = [src]
CMP r12,r10
BNE singleByteCompare
SUBS r14,r14,#4
STR r11,[r4], #4 @ r4 = [dst]
BGT xLoop
ADD r2,r2,r7 @ text += textSurfacePitch
ADD r3,r3,r5 @ src += vsPitch
ADD r4,r4,r6 @ dst += vmScreenWidth
SUBS r0,r0,#1
BGT yLoop
LDMFD r13!,{r4-r7,r9-r11,PC}
singleByteCompare:
MOV r9,r12,LSR #24 @ r9 = 1st byte of [text]
CMP r9,r10,LSR #24 @ if (r9 == mask)
MOVEQ r9,r11,LSR #24 @ r9 = 1st byte of [src]
ORR r12,r9,r12,LSL #8 @ r12 = combine r9 and r12
MOV r9,r12,LSR #24 @ r9 = 1st byte of [text]
CMP r9,r10,LSR #24 @ if (r9 == mask)
MOVEQ r9,r11,LSR #24 @ r9 = 1st byte of [src]
ORR r12,r9,r12,LSL #8 @ r12 = combine r9 and r12
MOV r9,r12,LSR #24 @ r9 = 1st byte of [text]
CMP r9,r10,LSR #24 @ if (r9 == mask)
MOVEQ r9,r11,LSR #24 @ r9 = 1st byte of [src]
ORR r12,r9,r12,LSL #8 @ r12 = combine r9 and r12
MOV r9,r12,LSR #24 @ r9 = 1st byte of [text]
CMP r9,r10,LSR #24 @ if (r9 == mask)
MOVEQ r9,r11,LSR #24 @ r9 = 1st byte of [src]
ORR r12,r9,r12,LSL #8 @ r12 = combine r9 and r12
STR r12,[r4],#4
SUBS r14,r14,#4
BGT xLoop
ADD r2,r2,r7 @ text += textSurfacePitch
ADD r3,r3,r5 @ src += vsPitch
ADD r4,r4,r6 @ dst += vmScreenWidth
SUBS r0,r0,#1
BGT yLoop
end:
LDMFD r13!,{r4-r7,r9-r11,PC}
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