int drawrun(CGContextRef context, struct BMAP_Run run, const void *buf) {
int i;
int x;
int offset;
x = run.startx;
offset = 0;
while (x < run.endx) {
int len;
if (sizeof(struct BMAP_Run) + (offset + 2)/2 > run.datalen) {
return -1;
}
len = readnibble(buf, offset++);
if (len >= 0 && len <= 7) { /* this is a sequence of different tiles */
len += 1;
if (sizeof(struct BMAP_Run) + (offset + len + 1)/2 > run.datalen) {
return -1;
}
for (i = 0; i < len; i++) {
/* draw terrain */
setterraincolor(context, readnibble(buf, offset++));
CGContextFillRect(context, CGRectMake(x++, run.y, 1, 1));
}
}
else if (len >= 8 && len <= 15) { /* this is a sequence of like tiles */
len -= 6;
if (sizeof(struct BMAP_Run) + (offset + 2)/2 > run.datalen) {
return -1;
}
/* draw terrain */
setterraincolor(context, readnibble(buf, offset++));
CGContextFillRect(context, CGRectMake(x, run.y, len, 1));
x += len;
}
else {
return -1;
}
}
if (sizeof(struct BMAP_Run) + (offset + 1)/2 != run.datalen) {
return -1;
}
return 0;
}
uint64_t poscorners(uint8_t* a){
uint8_t pos[cornercount];
memcpy(pos,a,cornercount);
sort(pos,pos+cornercount);
uint32_t x=binpos(pos,cornercount);
#if symred==1
__builtin_prefetch(srposcorn+x,0,0);
symcorners(a,readnibble(cornsymred[x/2],x%2));
#endif
uint32_t bmp=0;
uint8_t perm[cornercount]={0};
for(uint8_t i=0;i<cornercount;i++)
bmp+=(1<<a[i]);
for(uint8_t i=0;i<cornercount;i++){
uint32_t mask=bmp&((1<<a[i])-1); //create a mask including only x<a[i]
for(uint8_t j=0;j<24;j+=8) //and reduce a[i] appropiatly
perm[i]+=BitsSetTable256[(mask>>j)%256];
}
#if symred==1
return 46371*permpos(perm,8)+srposcorn[x];
#elif cornercount==8
return 735471*permpos(perm,8)+x;
#else
return 134596*permpos(perm,6)+x;
#endif
}