lpc.asm

基于TMS320F2812的AMR+RS编解码+OFDM调制解调源程序。是stand alone运行版本

*****************************************************************************
** Description:       lpc()      in lpc.c                                  **
**                                                                         **
** Inputs :                                                                **
**   *XAR3--Word16 st->levinsonSt[m+1]     : State struct                  **
**   *XAR2--Word16 x[]                     : Input signal                  **
**                                                                         **
** Outputs:                                                                **
**   *XAR1--Word16 st->levinsonSt[m+1]     : State struct                  **
**   *XAR4---Word16 a[]                    : predictor coefficients Q12    **   
**																		   **
** Return value :    		AL	                                           **
**                                                                         **
** Attribute    :       Cycles:36959          Pm: 18                       **
**               Modified Registers:XAR0--XAR7							   **
**                      @_buffer1--@_buffer1+47            		           **
**                      @_buffer2--@_buffer2+46                              **
**						ACC,P,T											   **
**                                                                         **
** Programmer   :       ZHOU Bei       (ok! MAR 18th,2003)                 **
*****************************************************************************

	 .global _lpc
	  
	 .ref _levinson
	 .ref _autocorr
	 .ref _lag_wind
	 
	 .ref M
	 .ref window_200_40
	 
	 .ref _buffer1
_lpc:
	 	;Autocorr(x, M, rHigh, rLow, window_200_40)
	 	PUSH	XAR3
	 	PUSH	XAR4
	 	
	 	MOVB	XAR1,#M
	 	MOVL	XAR4,#_buffer1+20             ;Save r_h
	 	MOVL	XAR5,#_buffer1+32             ;Save r_l
	 	MOVL	XAR3,#window_200_40
	 	LCR	    _autocorr
	 	
	 	;Lag_window(M, rHigh, rLow)
	 	MOVL	XAR2,#_buffer1+20             ;r_h
	 	MOVL	XAR3,#_buffer1+32             ;r_l
	 	LCR     _lag_wind
	    
	    ;Levinson(st->levinsonSt, rHigh, rLow, &a[MP1 * 3], rc)
	    POP		XAR4
	    POP		XAR1
	    MOVL	XAR2,#_buffer1+20             ;r_h
	 	MOVL	XAR3,#_buffer1+32             ;r_l
	    ADDB	XAR4,#33
	    MOVL	XAR5,#_buffer1+44             ;rc
	    LCR		_levinson
	    
	    MOV	    AL,#0
	    LRETR