Processor Description Languages

188 CHAPTER 8 TIE

In the aforementioned example TIE code, operation is a TIE language keyword

indicating the definition of a new instruction.The name or mnemonic of the instruc-

tion is

dotprod. This instruction has three operands from the 32-bit AR register file

of the Xtensa processor core. The two input operands

sample and coeff are read

from the register file, while the third operand

acc is both read and written by this

instruction.

The TIE instruction

dotprod is used in C code as illustrated here:

# include <xtensa/tie/dotprod.h>

unsigned int i, acc;

short *sample, *coeff;

for (i=0; i<N; i++) {

dotprod(acc, sample[i], coeff[i]);

}

The header file dotprod.h