AMD Typewriter x86 사용자 설명서

22007E/0—November 1999

;algorithm 1
MOV   EAX, m
MOV   EDX, dividend  
MOV   ECX, EDX
IMUL  EDX
ADD   EDX, ECX
SHR   ECX, 31
SAR   EDX, s
ADD   EDX, ECX           ;quotient in EDX

The derivation for the algorithm (a), multiplier (m), and shift
count (s), is found in the section “Signed Derivation for
Algorithm, Multiplier, and Shift Factor” on page 95.

;IN: EAX = dividend
;OUT:EAX = quotient
CMP

EAX, 800000000h

;CY = 1, if dividend >=0

SBB

EAX, –1

;Increment dividend if it is < 0

SAR

EAX, 1

;Perform a right shift

;IN:EAX = dividend
;OUT:EAX = quotient
CDQ

;Sign extend into EDX

AND

EDX, (2^n–1)

;Mask correction (use divisor –1)

ADD

EAX, EDX

;Apply correction if necessary

SAR

EAX, (n)

;Perform right shift by 
; log2 (divisor)

;IN:EAX = dividend
;OUT:EAX = quotient
CMP

EAX, 800000000h

;CY = 1, if dividend >= 0

SBB

EAX, –1

;Increment dividend if it is < 0

SAR

EAX, 1

;Perform right shift

NEG

EAX

;Use (x/–2) == –(x/2)

;IN:EAX = dividend
;OUT:EAX = quotient
CDQ

;Sign extend into EDX

AND

EDX, (2^n–1)

;Mask correction (–divisor –1)

ADD

EAX, EDX

;Apply correction if necessary

SAR

EAX, (n)

;Right shift by log2(–divisor)

NEG

EAX

;Use (x/–(2^n)) == (–(x/2^n))

;IN:EAX = dividend
;OUT:EAX = remainder
CDQ

;Sign extend into EDX

AND

EDX, 1

;Compute remainder

XOR

EAX, EDX

;Negate remainder if

SUB

EAX, EDX

;Dividend was < 0

MOV

[remainder], EAX