Processor Description Languages

190 CHAPTER 8 TIE

field s Inst[ 7: 4]

field t Inst[11: 8]

// Create operands that reference the AR register file

operand ars s { AR[s] }

operand arr r { AR[r] }

operand art t { AR[t] }

// Specify the opcode encoding for the instruction

field opc Inst[23:12]

opcode dotprod opc=12’h0A2

// Alternative syntax for instruction definition, when using

// explicit operand definitions

iclass dp { dotprod } { inout arr, in ars, in art }

reference dotprod {

assign arr = arr + ((ars[15:0]*art[15:0]) >> 8);

}

In the aforementioned description, field is a TIE keyword used to define three

bit fields named

r, s, and t, respectively. Each of these fields is 4-bits wide, and is

used to