Ethiopian multiplication: Difference between revisions

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@@ Line 2,275: / Line 2,275: @@
 BDC:010E 90             NOP
 BDC:010F 90             NOP
-;mulitplication routine
+;mulitplication routine starts here
 BDC:0110 89E5           MOV    BP,SP      ; prepare to get operands off stack
 BDC:0112 8B4E02         MOV    CX,[BP+02] ; Get the first operand
@@ Line 2,283: / Line 2,283: @@
 BDC:011E 7402           JZ     0122       ; no skip the next instruction
 BDC:0120 01D8           ADD    AX,BX     ; we are odd so add to the result
-BDC:0122 D1E9           SHR    CX,1      ; divide by 2
+BDC:0122 D1E3           SHL    BX,1      ; multiply by 2
-BDC:0124 D1E3           SHL    BX,1      ; multiply by 2
+BDC:0124 D1E9           SHR    CX,1      ; divide by 2 (if zr flag is set, we are done)
-BDC:0126 83F901         CMP    CX,+01    ; are we done (==1)
+BDC:0126 75F2           JNZ    011A      ; cx not 0, go back and do it again
-BDC:0129 75EF           JNZ    011A      ; no, go back and do it again
+BDC:0128 C3             RET              ; return with the result in AX
-BDC:012B 01D8           ADD    AX,BX     ; final add
-BDC:012D C3             RET              ; return with the result in AX
-;pretty small</lang>
+;pretty small, just 24 bytes </lang>