lesson3_c.c

dsp6713开发板的许多例程.对入门特别有用

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/* lesson3_c  -  Alignment info added for xptr & yptr                       */
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/* Results for Release 4.00:                                                */
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/*     When compiled with -k -mw -mh -o3:                                   */
/*          1 cycle per iteration - 4 MPYs 2 LDWs and 2 STHs each iteration */
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/*          Program info needed but not available:                          */
/*              None                                                        */
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/*          Program info available:                                         */
/*              Potential pointer aliasing info (restrict type qualifier)   */
/*              Loop count info - minimum trip count                        */
/*              Loop count info - max trip count factor                     */
/*              Alignment info - xptr and yptr aligned on a word boundary   */
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/*     When compiled with -k -mw -mh -o3 -pm -op2 with tutor_d              */
/*           1 cycle per iteration - All info available                     */
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#define WORD_ALIGNED(x) (_nassert(((int)(x) & 0x3) == 0))

void lesson3_c(short * restrict xptr, short * restrict yptr, short *zptr,
               short *w_sum, int N)
{
    int i, w_vec1, w_vec2;
    short w1, w2;
                                       
    WORD_ALIGNED(xptr);
    WORD_ALIGNED(yptr);                                   
                                       
    w1 = zptr[0];
    w2 = zptr[1];
    #pragma MUST_ITERATE(20, , 2);
    for (i = 0; i < N; i++)
    {
        w_vec1 =  xptr[i] * w1;
        w_vec2 =  yptr[i] * w2;
        w_sum[i] = (w_vec1 + w_vec2) >> 15;
    }
}