Texas Instruments TMS320C64X User Manual

Page 100

DSP_w_vec

4-72

Weighted Vector Sum

DSP_w_vec

Function

void DSP_w_vec(const short * restrict x, const short * restrict y, short m, short
* restrict r, short nr)

Arguments

x[nr]

Vector being weighted. Must be double-word aligned.

y[nr]

Summation vector. Must be double-word aligned.

Weighting factor

r[nr]

Output vector

Dimensions of the vectors. Must be multiple of 8 and

≥

Description

This routine is used to obtain the weighted vector sum. Both the inputs and
output are 16-bit numbers.

Algorithm

This is the C equivalent of the assembly code without restrictions. Note that
the assembly code is hand optimized and restrictions may apply.

void DSP_w_vec(short x[ ],short y[ ],short m,

short r[ ],short nr)

{

short i;

for (i=0; i

r[i] = ((m * x[i]) >> 15) + y[i];

}

Special Requirements

nr must be a multiple of 8 and

≥

Vectors x[ ] and y[ ] must be double-word aligned.

Implementation Notes

Bank Conflicts: No bank conflicts occur.

Interruptibility: The code is interrupt-tolerant but not interruptible.

Input is loaded in double-words.

Use of packed data processing to sustain throughput.

Benchmarks

Cycles

3 * nr/8 + 18

Codesize

144 bytes