; uint16 x = uint16 x / uint16 y ; ; Input: ; x, x+1  16 bit unsigned integer dividend (x  lsb, x+1  msb) ; y, y+1  16 bit unsigned integer divisor ; Output: ; x, x+1  16 bit unsigned integer quotient ; Temporary: ; counter ; x+2, x+3  16 bit remainder ; temp  remainder extension ; Size: 36 instructions ; Max timing: 6+16*(5+14+4)2+2+3=377 cycles div16by16 clr x+2 ;clear clr x+3 ;remainder div16by16loopinit clr temp ;clear remainder extension mov W, #16 mov counter, W stc ;first iteration will be subtraction div16by16loop ;shift in next result bit and shift out next ;dividend bit to remainder rl x ;shift lsb rl x+1 ;shift msb rl x+2 rl x+3 rl temp mov W, y sb x.0 jmp div16by16add ;subtract divisor from remainder sub x+2, W mov W, y+1 sc movsz W, ++y+1 sub x+3, W mov W, #1 sc sub temp, W jmp div16by16next div16by16add ;add divisor to remainder add x+2, W mov W, y+1 snc movsz W, ++y+1 add x+3, W mov W, #1 snc add temp, W div16by16next ;carry is next result bit decsz counter jmp div16by16loop ;shift in last bit rl x rl x+1 ret
See also:
; uint16 x = uint16 x / uint16 y
;
; Input:
; x, x+1  16 bit unsigned integer dividend (x  lsb, x+1  msb)
; y, y+1  16 bit unsigned integer divisor
; Output:
; x, x+1  16 bit unsigned integer quotient
; x+2, x+3  16 bit unsigned integer remainder
; Temporary:
; counter
; Size: 28 instructions
; Max timing: 4+16*(4+15+4)2+2+3=375 cycles
div16by16
clr x+2 ;clear
clr x+3 ;remainder
mov W, #16
mov counter, W
div16by16loop
;shift in next result bit and shift out next
;dividend bit to remainder
rl x
rl x+1
rl x+2
rl x+3
;subtract divisor from remainder
mov W, y
sub x+2, W
mov W, y+1
sc
movsz W, ++y+1
sub x+3, W
;if no borrow, set next quotient bit
snc
jmp div16by16next
;if borrow, clear next quotient bit and restore the remainder
;add divisor to remainder
mov W, y
add x+2, W
mov W, y+1
snc
movsz W, ++y+1
add x+3, W
clc
div16by16next
decsz counter
jmp div16by16loop
;shift in last result bit
rl x
rl x+1
ret
file: /Techref/scenix/lib/math/div/16by16ng.htm, 3KB, , updated: 2006/9/18 13:00, local time: 2020/9/29 20:37,

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