lsp_lsf.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:     _lsp_lsf in lsf_lsp.c                                  **
**                                                                         **
** Inputs                                                                  **
**                                                                         **
**   xar3---Word16 *lsp                                                    **
**   xar2---Word16 *lsf                                                    **
**                                                                         **
** Outputs:                                                                **
**                                                                         **
**   xar2---Word16 *lsf                                                    **
**                                                                         **
** Return value :       none                                               **
**                                                                         **
** Attribute    :       Cycles:2178(m=10) Pm:20                            **
**                      Modified Registers: acc,t,c,ar0,xar1,xar6,xar7     **
**                                                                         **
** Programmer   :       YANG zhiwei                                        **
*****************************************************************************

      .global _lsp_lsf
  
      .ref slope  
      .ref lsf_table
      .ref M
      
_lsp_lsf:  
	movl	xar6,#slope			;xar6 = pointer to slope
	movl	xar7,#lsf_table		;xar7 = pointer to lsf_table
	mov		ar1,#63 			;ind = 63
	mov		ar0,#M-1				;m = M
_loop_94:
	mov		ah,*+xar3[ar0]		;ah = lsp[i]

_loop_98:
	mov		al,ah
	sub	 	al,*+xar7[ar1]			;ah = lsp[i] - lsp_table[ind]
	bf    	_line_107,lt			;if ( lsp[i] - lsp_table[ind] ) < 0,jump to _line_107
    dec	 	ar1					;ind--
	bf		_loop_98,unc
_line_107:
    mov	 	t,al                   ;t = lsp[i] - lsp_table[ind]    
    mpy	 	acc,t,*+xar6[ar1]		;acc = ( lsp[i] - lsp_table[ind] ) * slope[ind]
    lsl	 	acc,#3+1					;acc left shift by 3+1
    
    add  	acc,#0x0800<<4
  	
	mov 	al,ar1
	lsl  	al,8  
    add  	ah,al          		;ah = ah + ind<<8
    
    mov	    *+xar2[ar0],ah			;lsf[i] = ah
    
    banz 	_loop_94,ar0--        ;ar1 = i not equal zero,jump to _loop_94,i-- 
    
    LRETR