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--- base:fastest_multiplication [2017-04-19 09:47] – repose
+++ base:fastest_multiplication [2017-04-19 09:59] – repose
@@ Line 15: / Line 15: @@
 ;and being less elegant and harder to follow.
 ;by Repose 2017
+;table generator by Graham
+;addition improvement suggested by JackAsser
+;data: 2044 bytes
+;zero page ram required: minimum 8 bytes, ideally 14
+;do_add: 30 bytes in zp, if used
+;time: 196 cycles, option for 192 if you use 30 more zp bytes for do_add
+;measurement method: branches/page boundary crossings were averaged
+;How to use:
+;put numbers in x/y and result is Y reg, X reg, z1, z0
 ;tables of squares
@@ Line 35: / Line 46: @@
 y0=$fd;multiplicand, 2 bytes
 y1=$fe
-z0=$80;product, 4 bytes
+z0=$80;product, 2 bytes
 z1=$81
-z2=$82
+;z2=$82 returned in X reg
-z3=$83
+;z3=$83 returned in Y reg
 ;Example showing use
@@ Line 154: / Line 165: @@
 sbc (p_invsqr_hi),y
 tay;x1*y1h;Y=z3, 30 cycles
-;17+33+31+17+31+30=159
+;17+33+31+17+31+30=159 cycles for main multiply part
+;jmp do_adds; can put do_adds in zp for a slight speed increase
 do_adds:
 ;-add the first two numbers of column 1