-while (p[0]) {
-p[-1]+=1;
-p[0]+=255;
-p[1]+=p[113];
-p[8]=p[113];
-p[113]=p[1];
+if (p[0]) {
+p[-1]=p[0];
 p[1]=0;
-p[8]+=1;
-p[9]=1;
-p[113]=p[8];
 p[8]=0;
+p[9]=1;
+p[113]+=p[0];
+p[0]=0;
 }

Note that it also figured out through other code that p[-1] must be 0 at entry. This happened several hundred lines before.

if (p[0]) {       while (p[0]) {
   p[-1]=p[0];       p[-1]+=1;
   p[1]=0;           p[0]+=255;
   p[8]=0;           p[1]+=p[113];
   p[9]=1;           p[8]=p[113];
   p[113]+=p[0];     p[113]=p[1];
   p[0]=0;           p[1]=0;
}                    p[8]+=1;
                     p[9]=1;
                     p[113]=p[8];
                     p[8]=0;
                  }