Texas Instruments TMS320C67 DSP Series Programmer's Reference Manual page 76

Special Requirements
Implementation Notes
Benchmarks
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nh is a multiple of 2 and greater than or equal to 4.
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nr is a multiple of 4.
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x and h are assumed to be aligned on a double-word boundary.
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The inner loop is unrolled twice and the outer loop is unrolled four times.
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Endianess: This code is little endian.
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Interruptibility: This code is interrupt-tolerant but not interruptible.
Cycles (nh/2)*nr + (nr/2)*5 + 9
For nh=24 and nr=64, cycles=937
For nh=20 and nr=32, cycles=409
Code size 480
(in bytes)
DSPF_sp_convol
DSPLIB Reference 4-51