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Fixed the comments to say where the actual Left-Hand Side and Right-Hand Side are put.
A description of positions [left, right] is appropriate more for C code than for Assembly code. (A description of timing [first argument, second argument] is more appropriate for the way that Assembly code is written.)
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@ -5,9 +5,7 @@
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;
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.export _cc65_umul8x8r16
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.import umul8x8r16, popa
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.include "zeropage.inc"
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.import umul8x8r16, popa, ptr1:zp
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;---------------------------------------------------------------------------
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@ -13,9 +13,9 @@
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;---------------------------------------------------------------------------
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; 16x16 => 32 signed multiplication routine.
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;
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; lhs rhs result result also in
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; LHS RHS result result also in
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; -------------------------------------------------------------
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; ptr1 ax ax:sreg
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; ax ptr1 ax:sreg
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;
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; There is probably a faster way to do this.
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;
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@ -13,14 +13,14 @@
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;---------------------------------------------------------------------------
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; 16x16 => 32 unsigned multiplication routine. Because the overhead for a
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; 16x16 => 16 unsigned multiplication routine is small, we will tag it with
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; the matching labels as well.
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; the matching labels, as well.
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;
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; routine lhs rhs result result also in
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; routine LHS RHS result result also in
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; -----------------------------------------------------------------------
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; umul16x16r32 ptr1 ax ax:sreg ptr1:sreg
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; umul16x16r32m ptr1 ptr3 ax:sreg ptr1:sreg
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; umul16x16r16 ptr1 ax ax ptr1
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; umul16x16r16m ptr1 ptr3 ax ptr1
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; umul16x16r32 ax ptr1 ax:sreg ptr1:sreg
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; umul16x16r32m ptr3 ptr1 ax:sreg ptr1:sreg
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; umul16x16r16 ax ptr1 ax ptr1
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; umul16x16r16m ptr3 ptr1 ax ptr1
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;
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; ptr3 is left intact by the routine.
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;
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@ -13,14 +13,14 @@
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;---------------------------------------------------------------------------
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; 8x16 => 24 unsigned multiplication routine. Because the overhead for a
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; 8x16 => 16 unsigned multiplication routine is small, we will tag it with
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; the matching labels as well.
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; the matching labels, as well.
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;
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; routine lhs rhs result result also in
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; routine LHS RHS result result also in
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; -----------------------------------------------------------------------
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; umul8x16r24 ptr1-lo ax ax:sreg-lo ptr1:sreg-lo
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; umul8x16r24m ptr1-lo ptr3 ax:sreg-lo ptr1:sreg-lo
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; umul8x16r24 ax ptr1-low ax:sreg-low ptr1:sreg-low
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; umul8x16r24m ptr3 ptr1-low ax:sreg-low ptr1:sreg-low
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;
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; ptr3 ist left intact by the routine.
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; ptr3 is left intact by the routine.
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;
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umul8x16r24:
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@ -1,7 +1,7 @@
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;
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; Ullrich von Bassewitz, 2010-11-02
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;
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; CC65 runtime: 8x8 => 16 multiplication
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; CC65 runtime: 8x8 => 16 unsigned multiplication
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;
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.export umul8x8r16, umul8x8r16m
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@ -9,11 +9,11 @@
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;---------------------------------------------------------------------------
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; 8x8 => 16 multiplication routine.
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; 8x8 => 16 unsigned multiplication routine.
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;
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; lhs rhs result result also in
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; LHS RHS result result in also
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; -------------------------------------------------------------
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; ptr1-lo ptr3-lo ax ptr1
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; .A (ptr3-low) ptr1-low .XA ptr1
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;
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umul8x8r16:
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@ -21,7 +21,7 @@ umul8x8r16:
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umul8x8r16m:
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lda #0 ; Clear byte 1
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ldy #8 ; Number of bits
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lsr ptr1 ; Get first bit of lhs into carry
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lsr ptr1 ; Get first bit of RHS into carry
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@L0: bcc @L1
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clc
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adc ptr3
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@ -30,8 +30,6 @@ umul8x8r16m:
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dey
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bne @L0
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tax
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stx ptr1+1 ; Result in a/x and ptr1
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stx ptr1+1 ; Result in .XA and ptr1
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lda ptr1 ; Load the result
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rts ; Done
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