fir_fixpt_asm.asm

用dsp解压mp3程序的算法

*****************************************************************
*fir_fxpt_asm.asm - An assembly program for C5000 CCS simulator
*
*****************************************************************
* Section allocation
*
		.def	 start
out_buffer	.usect  "out",300	; reserve 300 location for y
coeff		.usect  "coeff",96,1	; reserve 96 location for coefficients

		.sect  "coeff_table"
init_coeff	.int	 317,     26,   -125,   -132,     35,    149,     38,   -144,  -141
       		.int	 36,    131,     28,    -97,    -76,      6,      7,    -17,     48
       		.int	 90,    -65,   -252,   -105,    302,    364,   -176,   -636,   -229
      		.int	 646,    722,   -316,  -1102,   -375,   1034,   1111,   -463,  -1572
     		.int    -517,   1396,   1458,   -589,  -1955,   -627,   1658,   1693,   -667
    		.int	-2170,   -681,   1765,   1765,   -681,  -2170,   -667,   1693,   1658
     		.int	-627,  -1955,   -589,   1458,   1396,   -517,  -1572,   -463,   1111
     		.int	1034,   -375,  -1102,   -316,    722,    646,   -229,   -636,   -176
      		.int	364,    302,   -105,   -252,    -65,     90,     48,    -17,      7
        	.int	6,    -76,    -97,     28,    131,     36,   -141,   -144,     38
      		.int	149,     35,   -132,   -125,     26,    317
										
		.sect  "indata"
in_buffer       .copy  "in1_int.dat"    ; copy in1_int.dat to  memory label in_buffer

		.mmregs
		.text			; create code section
			
* Copy data to vector x using indirect addressing mode

start:
        STM     #0, SWWSR  
	SSBX	FRCT			; On fractional mode
	SSBX	SXM			; On sign extension mode
	RSBX	OVM			; On overflow mode
copy:	
	STM	#coeff,AR1		; AR1 pointing to coeff
	RPT	#95           		; repeat next instruction 96 times
	MVPD    init_coeff,*AR1+ 	; copy the init_coeff to coeff
	
* Setup the pointers to point to the coeff and data sample...
	STM	#coeff, AR2		; setup the pointer for coeff	
	STM	#in_buffer,  AR3	; setup the pointer for in_buffer
	STM	#out_buffer, AR4
	STM	#1, AR0
loop:
	STM	#299, BRC
	STM	#96, BK
	RPTB	fir_end-1
firloop:
        NOP
	MPY     *AR2+, *AR3+, A		; first multiply on 1st tap
	RPT	#94		        ; subsequent multiply for 95 other taps
	MAC	*AR2+0%, *AR3+, A	
	MAR	*+AR3(#-95)
	STH	A, *AR4+		; write result to memory location y	
fir_end:
	NOP