ref: 6aa7ebcf495bff8f6a4c7ebcac28058bd0b06aae
dir: /sys/src/libmemdraw/load.c/
#include <u.h> #include <libc.h> #include <draw.h> #include <memdraw.h> int loadmemimage(Memimage *i, Rectangle r, uchar *data, int ndata) { int y, l, lpart, rpart, mx, m, mr; Memdrawparam par; uchar *q; if(badrect(r) || !rectinrect(r, i->r)) return -1; memset(&par, 0, sizeof par); par.dst = i; par.r = r; hwdraw(&par); l = bytesperline(r, i->depth); if(ndata < l*Dy(r)) return -1; ndata = l*Dy(r); q = byteaddr(i, r.min); mx = 7/i->depth; lpart = (r.min.x & mx) * i->depth; rpart = (r.max.x & mx) * i->depth; m = 0xFF >> lpart; /* may need to do bit insertion on edges */ if(l == 1){ /* all in one byte */ if(rpart) m ^= 0xFF >> rpart; for(y=r.min.y; y<r.max.y; y++){ *q ^= (*data^*q) & m; q += i->width*sizeof(ulong); data++; } return ndata; } if(lpart==0 && rpart==0){ /* easy case */ for(y=r.min.y; y<r.max.y; y++){ memmove(q, data, l); q += i->width*sizeof(ulong); data += l; } return ndata; } mr = 0xFF ^ (0xFF >> rpart); if(lpart!=0 && rpart==0){ for(y=r.min.y; y<r.max.y; y++){ *q ^= (*data^*q) & m; if(l > 1) memmove(q+1, data+1, l-1); q += i->width*sizeof(ulong); data += l; } return ndata; } if(lpart==0 && rpart!=0){ for(y=r.min.y; y<r.max.y; y++){ if(l > 1) memmove(q, data, l-1); q[l-1] ^= (data[l-1]^q[l-1]) & mr; q += i->width*sizeof(ulong); data += l; } return ndata; } for(y=r.min.y; y<r.max.y; y++){ *q ^= (*data^*q) & m; if(l > 2) memmove(q+1, data+1, l-2); q[l-1] ^= (data[l-1]^q[l-1]) & mr; q += i->width*sizeof(ulong); data += l; } return ndata; }