📄 ulmul.s
字号:
|J. Test 1/81
|unsigned long multiply: c = a * b
.globl ulmul
.text
ulmul: link a6,#0
moveml #0x3000,sp@- |save d2,d3
movl a6@(8),d2 |d2 = a
movl a6@(12),d3 |d3 = b
clrl d0
movw d2,d0 |d0 = alo, unsigned
mulu d3,d0 |d0 = blo*alo, unsigned
movw d2,d1 |d1 = alo
swap d2 |swap alo-ahi
mulu d3,d2 |d2 = blo*ahi, unsigned
swap d3 |swap blo-bhi
mulu d3,d1 |d1 = bhi*alo, unsigned
addl d2,d1 |d1 = (ahi*blo + alo*bhi)
swap d1 |d1 =
clrw d1 | (ahi*blo + alo*bhi)*(2**16)
addl d1,d0 |d0 = alo*blo + (ahi*blo + alo*bhi)*(2**16)
3$: moveml sp@+,#0xC |restore d2,d3
unlk a6
rts
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