+
+static const uint8_t p_shifts[] PROGMEM = {
+ 0, 1, 2, 3, 4, 5, 6, 7
+};
+
+static const uint8_t q_shifts[] PROGMEM = {
+ 1, 3, 5, 7, 0, 2, 4, 6
+};
+
+
+static
+void shift_columns(uint8_t *a, PGM_VOID_P shifts){
+ uint8_t s;
+ uint8_t tmp[8];
+ uint8_t i,j;
+ for(i=0; i<8; ++i){
+ s = pgm_read_byte(shifts);
+ shifts = (uint8_t*)shifts + 1;
+ if(s==0){
+ continue;
+ }
+ for(j=0;j<8;++j){
+ tmp[j] = a[i+j*8];
+ }
+ for(j=0; j<8; ++j){
+ a[i+((j-s+8)%8)*8] = tmp[j];
+ }
+ }
+}
+
+
+