ex5p11.asm

用于DSK5416的程序

 
*************************************************************************
*  This program computes multiply and accumulate using direct addressing
*  mode.
*
*       y(n) = h(0)x(n) + h(1)x(n-1) + h(2)x(n-2)
*       
*       h(0), h(1), and h(2) are stored in data-memory locations starting at
*       location h and x(n), x(n-1), and x(n-2) are stored in data-memory
*       locations starting at location x. y(n) is saved in data-memory
*       location y (low 16 bits) and y + 1 (high 16 bits).
*
************************************************************************

        .global  _c_int00
    
x       .usect "Input Samples", 3
y       .usect "Output", 2    
h       .usect "Coefficients", 3
	
        .text

_c_int00:
        SSBX	SXM             ; Select sign extension mode
        LD      #h, DP          ; Select the data page for coefficients
        LD      @h, T           ; Get the coefficient h(0)
        LD      #x, DP          ; Select the data page for input samples
        MPY     @x, A           ; A = x(n)*h(0)
   
        LD      #h, DP          ; Select the data page for coefficients
        LD      @h+1,T          ; Get the coefficient h(1)
        LD      #x, DP          ; Select the data page for input signals
        MPY     @x+1, B         ; B = x(n-1)*h(1)
            
        ADD     A, B            ; B = x(n)*h(0) + x(n-1)*h(1)
       
        LD      #h, DP          ; Select the data page for coefficients
        LD      @h+2,T          ; Get the coefficient h(2)
        LD      #x, DP          ; Select the data page for input signals
        MPY     @x+2, A         ; A = x(n-2)*h(3)
        
        ADD     A, B            ; B = x(n)*h(0) + x(n-1)*h(1) + x(n-2)*h(3)
        
        LD      #y, DP          ; Select the data page for output
        STL     B, @y           ; Save low part of output
        STH     B, @y+1         ; Save high part of output
        NOP                     ; No operation
        
        .end