99 lines
2.5 KiB
NASM
99 lines
2.5 KiB
NASM
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
|
|
;;;
|
|
;;; Microsoft Research Singularity
|
|
;;;
|
|
;;; Copyright (c) Microsoft Corporation. All rights reserved.
|
|
;;;
|
|
;;; This file contains ARM-specific assembly code.
|
|
;;;
|
|
|
|
;
|
|
; void *
|
|
; memset( void *dest, int c, size_t count );
|
|
;
|
|
; The memset function sets the first count bytes of
|
|
; dest to the character c (value).
|
|
;
|
|
|
|
OPT 2 ; disable listing
|
|
INCLUDE kxarm.inc
|
|
OPT 1 ; reenable listing
|
|
|
|
value RN R1 ; int c
|
|
count RN R2
|
|
dest RN R3
|
|
temp RN R12
|
|
|
|
IF Thumbing
|
|
THUMBAREA
|
|
ENDIF
|
|
|
|
NESTED_ENTRY memset
|
|
PROLOG_END
|
|
|
|
IF Thumbing
|
|
; Switch from Thumb mode to ARM mode
|
|
DCW 0x4778 ; bx pc
|
|
DCW 0x46C0 ; nop
|
|
ENDIF
|
|
|
|
SUBS count, count, #4
|
|
MOV dest, R0 ;Save R0 for return
|
|
BLT BYTESET
|
|
|
|
AND value, value, #&FF
|
|
ORR value, value, value, LSL #8
|
|
CHECKALIGN ; 2-3 cycles
|
|
ANDS temp, dest, #3 ;Check alignment and fix if possible
|
|
BNE ALIGN
|
|
|
|
BLOCKSET ; 6-7 cycles
|
|
ORR value, value, value, LSL #16
|
|
SUBS count, count, #12
|
|
MOV temp, value
|
|
BLT BLKSET8
|
|
|
|
BLKSET16 ; 7 cycles/16 bytes
|
|
STMIA dest!, {value, temp}
|
|
SUBS count, count, #16
|
|
STMIA dest!, {value, temp}
|
|
BGE BLKSET16
|
|
|
|
BLKSET8 ; 4 cycles/8 bytes
|
|
ADDS count, count, #8
|
|
STMGEIA dest!, {value, temp}
|
|
SUBGE count, count, #8
|
|
|
|
BLKSET4
|
|
ADDS count, count, #4 ; 4 cycles/4 bytes
|
|
STRGE value, [dest], #4
|
|
|
|
BYTESET
|
|
ADDLTS count, count, #4
|
|
BEQ EXIT
|
|
|
|
STRB value, [dest], #1 ; 5 cycles/1-3bytes
|
|
CMP count, #2
|
|
STRGEB value, [dest], #1
|
|
STRGTB value, [dest], #1
|
|
|
|
EXIT
|
|
|
|
IF Interworking :LOR: Thumbing
|
|
BX lr
|
|
ELSE
|
|
MOV pc, lr
|
|
ENDIF
|
|
|
|
ALIGN ; 8 cycles/1-3 bytes
|
|
TST dest, #1 ;Check byte alignment
|
|
SUBNE count, count, #1
|
|
STRNEB value, [dest], #1
|
|
TST dest, #2 ;Check Half-word alignment
|
|
SUBNE count, count, #2
|
|
STRNEH value, [dest], #2
|
|
B BLOCKSET
|
|
|
|
ENTRY_END
|
|
END
|