getcor.asm

文件为美军4800bps语音压缩编码标准在TI的DSP芯片TMS320C5X上的实时实现源代码。

;----AR1->(long)COR[11]**,  AR0->SIGNAL[240]
;===================================
;----used AR7,AR6,AR2,SPM 0,
;----AR0, AR1, AR2, AR6, AR7, BMAR, TREG0, PREG, ACC, ACCB
;----IBUF
;===================================
;COR	.USECT "WARRAY",11*2
;===================================
GETCOR
	LAR AR0,#SIGNAL
	LAR AR1,#COR		;AR1->COR,AR0->SIGNAL
	LAMM AR0
	SAMM AR2
	;LAR AR6,#HFLEN_1	;120-i,AR6--
	 lacc #HFLEN_1
	 sacl IBUF
	LAR AR7,#10		;REPEAT COUNT
	SPM 3
	;------------ARP=0
	;-------Begin calculating c0
	MAR *,AR0
	ZAP
	RPT #HFLEN_1
	  MAC #SIGNAL,*+
	APAC			;120 values sum ACC+=PREG*(2**shift)
	;SFR			;ACC>>=1
	SACB			;ACC->ACCB
	;-----------
	ZAP
	;RPT AR6			;AR6->RPTC
	rpt IBUF
	  MAC #SIGNAL+120,*+
	APAC			;(AR6) values sum ACC+=PREG*(2**shift)
	;SFR			;ACC>>=1
	ADDB			;ACC+=ACCB
	;----------------
	SUB #256
	BCND GLT256,LEQ		;JUMP IF C0<256
	;-----IF C0>=256-----------
	;----GET C----------
	ADD #256
	MAR *,AR1
	SACL *+   		;ARP=1
	SACH *+,0,AR6		;ARP=6
	;-----------------
	lacc IBUF
	sub #1
	sacl IBUF
	MAR *-,AR2		;AR6--,120-i
	MAR *+,AR7		;AR2++,*signal++
	MAR *-,AR0
	LAMM AR2
	SAMM AR0
	;LAR AR0,AR2		;AR2->AR0 ,ARP=0
	B COR_256
	;----IF C0<256-----------
GLT256
	SPM 0
	LAR AR0,#SIGNAL
	;--------------------ARP=0
COR_256
	ZAP
	RPT #HFLEN_1
	  MAC #SIGNAL,*+
	APAC			;120 values sum ACC+=PREG*(2**shift)
	;SFR			;ACC>>=1
	SACB			;ACC->ACCB
	;-----------
	ZAP
	;RPT AR6			;AR6->RPTC
	rpt IBUF
	  MAC #SIGNAL+120,*+
	APAC			;120 values sum ACC+=PREG*(2**shift)
	;SFR			;ACC>>=1
	ADDB			;ACC+=ACCB
	;----GET C----------
	MAR *,AR1
	SACL *+   		;ARP=1
	SACH *+,0,AR6		;ARP=6
	;-----------------
	lacc IBUF
	sub #1
	sacl IBUF
	MAR *-,AR2		;AR6--,120-i
	MAR *+,AR7		;AR2++,*signal++
	;LAR AR0,AR2		;AR2->AR0 ,ARP=7
	LAMM AR2
	SAMM AR0
	BANZ COR_256,*-,AR0
	RETD
	 SPM 0
	 NOP