diff options
Diffstat (limited to 'test/rotate.s')
| -rw-r--r-- | test/rotate.s | 61 |
1 files changed, 61 insertions, 0 deletions
diff --git a/test/rotate.s b/test/rotate.s new file mode 100644 index 0000000..6115e94 --- /dev/null +++ b/test/rotate.s @@ -0,0 +1,61 @@ +; Test rol, and ror. + +.org 0 +count: + .res 1 +tmp: + .res 8 + +.org $8000 +reset: + cps ; + ldx.w #$FFFF ; + txs ; + and #0 ; + tax ; + tab ; + tay ; + + +start: + ldb #8 ; Set the loop count to 8. +@loop: + lda #$AA ; Set A to magic byte. + deb ; Decrement the loop count. + beq @savemagic ; Save the magic number, if the loop count is zero. + lsl #8 ; Shift the magic number by one byte, if the loop count is non zero. + bra @loop ; Keep looping. +@savemagic: + sta.q tmp ; Save the magic number. + + +rotate: + ldb #0 ; Reset B. +@loop: + and #0 ; Reset A. + lda #$40 ; Set the shift count to 64. + sta count ; + lda.q tmp ; Get our magic number. + inb ; Increment our shift amount by one. + cpb #$40 ; Is the shift amount greater than, or equal to 64? + bcs rotate ; Yes, so reset B. +@rotl: + rol b ; Rotate the magic number left by our shift amount. + dec count ; Decrement the shift count. + beq @rotr ; Start rotating right, if the shift count is zero. + bra @rotl ; Keep looping, if the shift count is non zero. +@rotr: + and #0 ; Reset A. + lda #$40 ; Set the shift count to 64. + sta count ; + lda.q tmp ; Get our magic number. +@rotr2: + ror b ; Rotate the magic number right by our shift amount. + dec count ; Decrement the shift count. + beq @loop ; Increment the shift amount, if the shift count is zero. + bra @rotr2 ; Keep looping, if the shift count is non zero. + +.org $FFC0 +.qword reset +a +d |