memset.s

Newlib 嵌入式 C库 标准实现代码

!
! Fast SH memset
!
! by Toshiyasu Morita ([e-mail])
!
! SH5 code by J"orn Rennecke ([e-mail])
! Copyright 2002 SuperH Ltd.
!

#include "asm.h"

ENTRY(memset)
#if __SHMEDIA__
	pta/l multiquad, tr0
	ptabs r18, tr2

	andi r2, -8, r25
	add r2, r4, r5
	addi r5, -1, r20    // calculate end address.
	andi r20, -8, r20
	cmveq r4, r25, r20
	bne/u r25, r20, tr0 // multiquad

!	This sequence could clobber volatile objects that are in the same
!	quadword as a very short char array.
!	ldlo.q r2, 0, r7
!	shlli r4, 2, r4
!	movi -1, r8
!	SHHI r8, r4, r8
!	SHHI r8, r4, r8
!	mcmv r7, r8, r3
!	stlo.q r2, 0, r3

	pta/l setlongs, tr0
	movi 4, r8
	bgeu/u r4, r8, tr0
	pta/l endset, tr0
	beqi/u r4, 0, tr0
	st.b r2, 0, r3
	beqi/u r4, 1, tr0
	nop
	st.b r2, 1, r3
	beqi/l r4, 2, tr0
	st.b r2,2,r3
endset: blink tr2, r63
setlongs:
	mshflo.b r3, r3, r3
	mperm.w r3, r63, r3	// Fill pattern now in every byte of r3
	stlo.l r2, 0, r3
	nop
	nop
	sthi.l r5, -1, r3
	blink tr2, r63

multiquad:
	mshflo.b r3, r3, r3
	mperm.w r3, r63, r3	// Fill pattern now in every byte of r3
	pta/l lastquad, tr0
	stlo.q r2, 0, r3
	sub r20, r25, r24
	movi 64, r9
	beqi/u r24, 8, tr0 // lastquad
	pta/l loop, tr1
	addi r20, -7*8, r8 // loop end address; This might overflow, so we need
	                   // to use a different test before we start the loop
	bgeu/u r24, r9, tr1// loop
	st.q r25, 8, r3
	shlri r24, 4, r24
	st.q r20, -8, r3
	beqi/u r24, 1, tr0 // lastquad
	st.q r25, 16, r3
	st.q r20, -16, r3
	beqi/u r24, 2, tr0 // lastquad
	st.q r25, 24, r3
	st.q r20, -24, r3
lastquad:
	sthi.q r5, -1, r3
	blink tr2,r63

loop:
	alloco r25, 32
	st.q r25, 8, r3
	st.q r25, 16, r3
	st.q r25, 24, r3
	st.q r25, 32, r3
	addi r25, 32, r25
	bgeu/l r8, r25, tr1 // loop

	st.q r20, -40, r3
	st.q r20, -32, r3
	st.q r20, -24, r3
	st.q r20, -16, r3
	st.q r20, -8, r3
	sthi.q r5, -1, r3
	blink tr2,r63
#else /* ! SHMEDIA, i.e. SH1 .. SH4 / SHcompact */
! Entry: r4: destination pointer
!        r5: fill value
!        r6: byte count
!
! Exit:  r0-r3: trashed
!

! This assumes that the first four bytes of the address space (0..3) are
! reserved - usually by the linker script.  Otherwise, we would had to check
! for the case of objects of the size 12..15 at address 0..3 .

#ifdef __SH5__
#define DST r2
#define VAL r3
#define CNT r4
#define TMP r5
#else
#define DST r4
#define VAL r5
#define CNT r6
#define TMP r2
#endif

	mov	#12,r0	! Check for small number of bytes
	cmp/gt	CNT,r0
	mov	DST,r0
	SL(bt, L_store_byte_loop_check0, add DST,CNT)

	tst	#3,r0	! Align destination
	SL(bt,	L_dup_bytes, extu.b r5,r5)
	.balignw 4,0x0009
L_align_loop:
	mov.b	VAL,@r0
	add	#1,r0
	tst	#3,r0
	bf	L_align_loop

L_dup_bytes:	
	swap.b	VAL,TMP	! Duplicate bytes across longword
	or	TMP,VAL
	swap.w	VAL,TMP
	or	TMP,VAL

	add	#-16,CNT

	.balignw 4,0x0009
L_store_long_loop:
	mov.l	VAL,@r0	! Store double longs to memory
	cmp/hs	CNT,r0
	mov.l	VAL,@(4,r0)
	SL(bf, L_store_long_loop, add #8,r0)

	add	#16,CNT

L_store_byte_loop_check0:
	cmp/eq	CNT,r0
	bt	L_exit
	.balignw 4,0x0009
L_store_byte_loop:
	mov.b	VAL,@r0	! Store bytes to memory
	add	#1,r0
	cmp/eq	CNT,r0
	bf	L_store_byte_loop

L_exit:
	rts
	mov	r4,r0
#endif /* ! SHMEDIA */