Example of SIMD Optimization Phases

static unsigned char sa,sr,sg,sb;
static short da,dr,dg,db;
static short k;

static void
hLineRight(unsigned char *p,int n,
           unsigned char a,short ea,
           unsigned char r,short er,
           unsigned char g,short eg,
           unsigned char b,short eb) {
  while(n!=0) {
    *p++=b; *p++=g; *p++=r; *p++=a;
    a+=sa; r+=sr; g+=sg; b+=sb;
    if((ea+=da)>=0) { a++; ea-=k; }
    if((er+=dr)>=0) { r++; er-=k; }
    if((eg+=dg)>=0) { g++; eg-=k; }
    if((eb+=db)>=0) { b++; eb-=k; }
    --n;
  }
}