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--- base:fastest_multiplication [2023-08-21 05:18] – repose
+++ base:fastest_multiplication [2023-12-11 12:19] – repose
@@ Line 10: / Line 10: @@
 Times above need to add 6 for rts \\
 Note: updated 2023; corrected code, typos and timings \\
-*Timing approximate for external code
+*Timing approximate for external code \\
+This is the winner out of 120 published algorithms as independently tested here:
+https://github.com/TobyLobster/multiply_test
 <code>
@@ Line 27: / Line 29: @@
 ;How to use:
-;put numbers in x/y and result is Y reg, A reg, z1, z0
+;put numbers in x/y and result is Y reg (z3), A reg (z2), z1, z0
 ;tables of squares
@@ Line 50: / Line 52: @@
 z0=$80;product, 2 bytes
 z1=$81
-z2=$82 ;returned in X reg
+z2=$82 ;returned in A reg
 z3=$83 ;returned in Y reg
@@ Line 170: / Line 172: @@
 lda (p_sqr_hi),y
 sbc (p_invsqr_hi),y
-tay;x1*y1h;Y=z3, 30.992 cycles
+tay;Y=x1*y1h, 30.992 cycles
 ;17+34+33+17+33+31=164.97 cycles for main multiply part (minimum=157, maximum=173)
@@ Line 184: / Line 186: @@
 c2a:	lda #0
 c2b:	adc #0
-	tax;X=z2, 6 cycles
+	tax
-	bcc c1c;3/6 avg 4.5
+	bcc c1c;9
 	iny;z3++
-	clc
+	clc;(+3) taken 7% of the time, 3*.07=+.21
 ;-add last number of column 1
@@ Line 195: / Line 197: @@
 ;-add last number of column 2
-	txa;A=z2
+	txa
 c2c:	adc #0
-	;A=z2, 6
+	;A=z2
-	bcc fin;3/4 avg 3.5
+	bcc fin;7
-	iny;z3++
+	iny;(+1) taken 42% of the time, 1*.42=.42
 ;Y=z3, A=z2
-;33.63
+;add partials part total cycles=33.63 (minimum=33, maximum=37)
-fin:	rts
+;total time=164.97+33.63=198.6
+fin:	rts;add 6 to include this (204.6)
 Diagram of the additions