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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
.global asmCopy8Col
@ 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-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
MOV r8,#0x7F
ORR r8, r8, r8, LSL #8
ORR r8, r8, r8, LSL #16 @ r8 = 7f7f7f7f
STR r1,[r13,#-4]! @ Stack width
B xLoop
notEntirelyTransparent:
AND r14,r9, r8 @ r14 = mask & 7f7f7f7f
ADD r14,r14,r8 @ r14 = (mask & 7f7f7f7f)+7f7f7f7f
ORR r14,r14,r9 @ r14 |= mask
BIC r14,r14,r8 @ r14 &= 80808080
ADD r14,r8, r14,LSR #7 @ r14 = (rx>>7) + 7f7f7f7f
EOR r14,r14,r8 @ r14 ^= 7f7f7f7f
@ So bytes of r14 are 00 where source was matching value,FF otherwise
BIC r11,r11,r14
AND r12,r12,r14
ORR r12,r11,r12
STR r12,[r4],#4
SUBS r1,r1,#4
BLE endXLoop
xLoop:
LDR r12,[r2],#4 @ r12 = temp = [text]
LDR r11,[r3],#4 @ r11 = [src]
@ Stall
EORS r9, r12,r10 @ r9 = mask = temp ^ TRANSPARENCY
BNE notEntirelyTransparent
SUBS r1, r1, #4
STR r11,[r4], #4 @ r4 = [dst]
BGT xLoop
endXLoop:
ADD r2,r2,r7 @ text += textSurfacePitch
ADD r3,r3,r5 @ src += vsPitch
ADD r4,r4,r6 @ dst += vmScreenWidth
SUBS r0,r0,#1
LDRGT r1,[r13] @ r14 = width
BGT xLoop
ADD r13,r13,#4
end:
LDMFD r13!,{r4-r11,PC}
@ ARM implementation of asmCopy8Col
@
@ C prototype would be:
@
@ extern "C" void asmCopy8Col(byte *dst,
@ int dstPitch,
@ const byte *src,
@ int height);
@
@ In addition, we assume that src and dst are both word (4 byte)
@ aligned. This is the same assumption that the old 'inline' version
@ made.
asmCopy8Col:
@ r0 = dst
@ r1 = dstPitch
@ r2 = src
@ r3 = height
STMFD r13!,{r14}
SUB r1,r1,#4
TST r3,#1
ADDNE r3,r3,#1
BNE roll2
yLoop2:
LDR r12,[r2],#4
LDR r14,[r2],r1
STR r12,[r0],#4
STR r14,[r0],r1
roll2:
LDR r12,[r2],#4
LDR r14,[r2],r1
SUBS r3,r3,#2
STR r12,[r0],#4
STR r14,[r0],r1
BNE yLoop2
LDMFD r13!,{PC}
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