I'm just playing with my MC 68HC11; in C i can perform a simple byte swap by doing something like this:
swapped = ((num>>24)&0xff) | // move byte 3 to byte 0 ((num<<8)&0xff0000) | // move byte 1 to byte 2 ((num>>8)&0xff00) | // move byte 2 to byte 1 ((num<<24)&0xff000000); // byte 0 to byte 3
But now i want to achieve something a little harder using assembly code:
I created an ARRAY and added some values (using little endian logic). I want to read that ARRAY and swap all the values into big endian logic and store them inside "BIGENDIAN". I was thinking something like this:
RWM EQU $0 ROM EQU $C000 RESET EQU $FFFE ORG RWM BIGENDIAN RMB 16 ORG ROM Main: END BRA END ARRAY DW $0124,$FEEB,$0011,$0070,$ABEF,$074B,$8004,$8080 ORG RESET DW Main
I tried but it did not work properly.
DW creates 16-bit words.
(Your C example is for 32-bit words.)
For 16-bit one possibility is this:
RAM equ $0 ROM equ $C000 Vreset equ $FFFE org RAM BIGENDIAN rmb 16 org ROM ARRAY dw $0124,$FEEB,$0011,$0070,$ABEF,$074B,$8004,$8080 Start ldx #ARRAY ;X -> source ldy #BIGENDIAN ;Y -> destination Loop ldd ,x ;A = MSB, B = LSB (big endian view) staa 1,y stab ,y ; one alternative for above two instructions ; pshb ; tab ; pula ; std ,y ldab #2 ;B = word size abx ;X -> next word aby ;Y -> next word cpx #ARRAY+::ARRAY blo Loop Done bra * org Vreset dw Start
If you meant 32-bit words, so two 16-bit should be considered one word, I'll revise.