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libmemdraw: improve readbyte() and writebyte() routines

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remove unused memsetb() routine.

replace foo ? 1 : 0 with foo != 0

avoid double calculation of rgb components in readbyte()

handle byte aligned color components in writebyte()
which lets us avoid the read-modify-write and the shifting.
surprisingly, the branches in the loop are way less important
than avoiding the memory access.

this change makes ganes/snes playable at -3 scaling.
This commit is contained in:
cinap_lenrek 2014-04-12 21:59:52 +02:00
parent a321204a20
commit 96a94c3891
1 changed files with 38 additions and 18 deletions
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56
sys/src/libmemdraw/draw.c
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@ -1496,7 +1496,7 @@ readcmap(Param *p, uchar *buf, int y)
end = p->bytey0e + y*p->bwidth;
cmap = p->img->cmap->cmap2rgb;
convgrey = p->convgrey;
copyalpha = (p->img->flags&Falpha) ? 1 : 0;
copyalpha = (p->img->flags&Falpha) != 0;
w = buf;
dx = p->dx;
@ -1603,7 +1603,7 @@ readbyte(Param *p, uchar *buf, int y)
convgrey = p->convgrey; /* convert rgb to grey */
isgrey = img->flags&Fgrey;
alphaonly = p->alphaonly;
copyalpha = (img->flags&Falpha) ? 1 : 0;
copyalpha = (img->flags&Falpha) != 0;
DBG print("copyalpha %d alphaonly %d convgrey %d isgrey %d\n", copyalpha, alphaonly, convgrey, isgrey);
/* if we can, avoid processing everything */
@ -1655,16 +1655,17 @@ DBG print("g %x %x %x\n", ured, ugrn, ublu);
*w++ = RGB2K(ured, ugrn, ublu);
DBG print("%x\n", w[-1]);
}else{
*w++ = brepl[(u >> img->shift[CBlue]) & img->mask[CBlue]];
*w++ = grepl[(u >> img->shift[CGreen]) & img->mask[CGreen]];
*w++ = rrepl[(u >> img->shift[CRed]) & img->mask[CRed]];
w[0] = ublu;
w[1] = ugrn;
w[2] = ured;
w += 3;
}
}
r += nb;
if(r == end)
r = begin;
}
b.alpha = copyalpha ? buf : &ones;
b.rgba = (ulong*)buf;
if(alphaonly){
@ -1708,7 +1709,6 @@ writebyte(Param *p, uchar *w, Buffer src)
dx = p->dx;
nb = img->depth/8;
mask = (nb==4) ? 0 : ~((1<<img->depth)-1);
isalpha = img->flags&Falpha;
isgrey = img->flags&Fgrey;
@ -1720,6 +1720,37 @@ writebyte(Param *p, uchar *w, Buffer src)
adelta = 0;
}
if((img->flags&Fbytes) != 0){
int ogry, ored, ogrn, oblu, oalp;
ogry = img->shift[CGrey]/8;
ored = img->shift[CRed]/8;
ogrn = img->shift[CGreen]/8;
oblu = img->shift[CBlue]/8;
oalp = img->shift[CAlpha]/8;
for(i=0; i<dx; i++){
if(isgrey){
w[ogry] = *grey;
grey += delta;
} else {
w[ored] = *red;
w[ogrn] = *grn;
w[oblu] = *blu;
red += delta;
grn += delta;
blu += delta;
}
if(isalpha){
w[oalp] = *alpha;
alpha += adelta;
}
w += nb;
}
return;
}
mask = (nb==4) ? 0 : ~((1<<img->depth)-1);
for(i=0; i<dx; i++){
u = w[0] | (w[1]<<8) | (w[2]<<16) | (w[3]<<24);
DBG print("u %.8lux...", u);
@ -2016,17 +2047,6 @@ boolcopyfn(Memimage *img, Memimage *mask)
/*
* Optimized draw for filling and scrolling; uses memset and memmove.
*/
static void
memsetb(void *vp, uchar val, int n)
{
uchar *p, *ep;
p = vp;
ep = p+n;
while(p<ep)
*p++ = val;
}
static void
memsets(void *vp, ushort val, int n)
{