;*********************************************** ; ; 8 bit Fast Square root ; ; Input: x (not changed) ; Output: y ; Temporary: Temp ; ; Instructions: 29 ; Execution time (includng return): ; 31 cycles ; ; August 9, 2000 by Nikolai Golovchenko ; ;*********************************************** sqrt8fast mov W, x ;1 mov Temp, W clr y ;find bit 3 of result mov W, #$40 ;4 sub Temp, W rl y sb y.0 add Temp, W ;restore Temp ;find bit 2 of result or W, #$10 ;9 sb y.0 xor W, #$40 sub Temp, W rl y sb y.0 add Temp, W ;restore Temp ;find bit 1 of result mov W, <>y ;y = 16 * result<3:2> or W, #$04 ;set bit 1 sub Temp, W ;Temp - (4 * (4 * result<3:2> + 1)) rl y ;store result sb y.0 ;20 add Temp, W ;restore Temp ;find bit 0 of result xor W, #$0E ;set bit 0 and compensate for set bit 0 in previous substaction sb y.0 ;24 xor W, #$08 rl Temp ;shift left the remainder (carry ignored) sub Temp, W ;Temp - (4 * (4 * result<3:1> + 1)) rl y ;if borrow clear bit 0 and set otherwise ret ;31 ;***********************************************
file: /Techref/scenix/lib/math/sqrt/sqrt8fast_sx.htm, 2KB, , updated: 2004/6/10 14:40, local time: 2024/8/16 17:31,
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Ashley Roll has put together a really nice little unit here. Leave off the MAX232 and keep these handy for the few times you need true RS232! |
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