diff options
Diffstat (limited to 'test/popcnt.s')
| -rw-r--r-- | test/popcnt.s | 44 |
1 files changed, 44 insertions, 0 deletions
diff --git a/test/popcnt.s b/test/popcnt.s new file mode 100644 index 0000000..7682653 --- /dev/null +++ b/test/popcnt.s @@ -0,0 +1,44 @@ +; Calculate population count/hamming weight. + +.org $1000 + +popcnt: + ldb #0 ; Reset bit count. + pha.q ; Create a temporary variable. + cmp #0 ; Set the status flags. +@loop: + beq @end ; There are no more one bits left, so we're done. + dec.q sp+1 ; Decrement the temp variable. + dec.q sp+1 ; Decrement the temp variable. + inb ; Increment the bit count. + and.q sp+1 ; AND value with value-1. + sta.q sp+1 ; Place it back in the temp variable. + bra @loop ; Keep looping. +@end: + pla.q ; Pull/Pop the temp variable off the stack. + tba ; Return the bit count. + rts ; End of popcnt. + + +reset: + cps ; Boilerplate reset code. + ldx.w #$FFFF ; + txs ; + and #0 ; Reset A. + tab ; Reset B. + tax ; Reset X. + tay ; Reset Y. +main: + pha.q ; Save A. + jsr popcnt ; Get population count. + tay ; Save it in Y. + pla.q ; Get A back. + inc ; Increment A by one. + bra main ; Keep looping. + + +.org $FFC0 +.qword reset + +a +d |