negate.asm

来自「包含几个高效的矢量运算的数学函数」· 汇编 代码 · 共 50 行

	.include "ccall.asm"

	.def _ti_negate
_ti_negate:
	setc OVM			; Set saturation mode to handle -32768 case.

	pre_ccall 3,AR_X,AR_Z,AR_N
	
; Compute N%7 to make N divisible by 8 in the unrolled loop	
	sar AR_N,*			; stack[0]=N         
	lacl *+				; acc=N
	and #07h			; acc&=0111b - Unroll 8 iterations
	sacl *-				; stack[1] = N % 0111b
	lacc *,13			; acch=N>>3
	sach *+				; stack[0]=N>>3
	lar AR_N,*-,AR_N		; AR_N = stack[1] = N%7
	banz NEXT0,AR_X		; Skip loop if AR_X = 0
	b NEXT1

NEXT0:                     
	lacc *+,16,AR_Z		; ACC = x[AR_X++];
	neg
	sach *+,AR_N
	; while(N--)
	banz NEXT0,AR_X

NEXT1:
	mar *,AR_STACK
	lar AR_N,*,AR_N ; AR_N = stack[0]=N>>3 
	banz NEXT2,AR_X		; Go to 8x loop if AR_X > 0
	b DONE
	
NEXT2:                     
	.loop 7
	lacc *+,16,AR_Z		; ACC = x[AR_X++];
	neg
	sach *+,AR_X
	.endloop
	lacc *+,16,AR_Z		; ACC = x[AR_X++];
	neg
	sach *+,AR_N
	; while(N--)
	banz NEXT2,AR_X

DONE:
; Restore OVM
	clrc ovm

	post_ccall 3