singrdk/base/Kernel/Native/arm/Crt/__udiv.asm

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2.5 KiB
NASM
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2008-11-17 18:29:00 -05:00
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;
;;; Microsoft Research Singularity
;;;
;;; Copyright (c) Microsoft Corporation. All rights reserved.
;;;
;;; This file contains ARM-specific assembly code.
;;;
; Unsigned divide of r1 by r0: returns quotient in r0, remainder in r1
; Destroys a3, a4
OPT 2 ; disable listing
INCLUDE kxarm.inc
OPT 1 ; reenable listing
IMPORT __rt_div0
IF Thumbing
AREA |.text|, CODE, READONLY, THUMB
ELSE
AREA |.text|, CODE, READONLY
ENDIF
EXPORT |__rt_udiv| [FUNC]
|__rt_udiv|
IF Thumbing
; Switch from Thumb mode to ARM mode
DCW 0x4778 ; bx pc
DCW 0x46C0 ; nop
ENDIF
MOV a4, #0
MOVS a3, r0
BEQ DivideByZero
while
CMP a3, r1, LSR #8
MOVLS a3, a3, LSL #8
BLO while
CMP a3, r1, LSR #1
BHI goto7
CMP a3, r1, LSR #2
BHI goto6
CMP a3, r1, LSR #3
BHI goto5
CMP a3, r1, LSR #4
BHI goto4
CMP a3, r1, LSR #5
BHI goto3
CMP a3, r1, LSR #6
BHI goto2
CMP a3, r1, LSR #7
BHI goto1
loop
MOVHI a3, a3, LSR #8
CMP r1, a3, LSL #7
ADC a4, a4, a4
SUBCS r1, r1, a3, LSL #7
CMP r1, a3, LSL #6
goto1
ADC a4, a4, a4
SUBCS r1, r1, a3, LSL #6
CMP r1, a3, LSL #5
goto2
ADC a4, a4, a4
SUBCS r1, r1, a3, LSL #5
CMP r1, a3, LSL #4
goto3
ADC a4, a4, a4
SUBCS r1, r1, a3, LSL #4
CMP r1, a3, LSL #3
goto4
ADC a4, a4, a4
SUBCS r1, r1, a3, LSL #3
CMP r1, a3, LSL #2
goto5
ADC a4, a4, a4
SUBCS r1, r1, a3, LSL #2
CMP r1, a3, LSL #1
goto6
ADC a4, a4, a4
SUBCS r1, r1, a3, LSL #1
goto7
CMP r1, a3
ADC a4, a4, a4
SUBCS r1, r1, a3
CMP a3, r0
BNE loop
MOV r0, a4
end
IF Interworking :LOR: Thumbing
BX lr
ELSE
MOV pc, lr
ENDIF
;
; Divide by zero has occurred. Raise an exception
; call RaiseException(STATUS_INTEGER_DIVIDE_BY_ZERO, 0, 0, NULL)
;
DivideByZero
ldr r12, =__rt_div0
ldr r0, =0xC0000094
mov r1, #0
mov r2, #0
mov r3, #0
IF Thumbing
bx r12
ELSE
mov pc, r12
ENDIF
END