1 %default {"preinstr":"", "result":"a0", "chkzero":"0"} 2 /* 3 * Generic 32-bit "lit16" binary operation. Provide an "instr" line 4 * that specifies an instruction that performs "result = a0 op a1". 5 * This could be an MIPS instruction or a function call. (If the result 6 * comes back in a register other than a0, you can override "result".) 7 * 8 * If "chkzero" is set to 1, we perform a divide-by-zero check on 9 * CCCC (a1). Useful for integer division and modulus. 10 * 11 * For: add-int/lit16, rsub-int, mul-int/lit16, div-int/lit16, 12 * rem-int/lit16, and-int/lit16, or-int/lit16, xor-int/lit16 13 */ 14 /* binop/lit16 vA, vB, #+CCCC */ 15 lh a1, 2(rPC) # a1 <- sign-extended CCCC 16 ext a2, rINST, 8, 4 # a2 <- A 17 ext a3, rINST, 12, 4 # a3 <- B 18 GET_VREG a0, a3 # a0 <- vB 19 .if $chkzero 20 beqz a1, common_errDivideByZero # is second operand zero? 21 .endif 22 FETCH_ADVANCE_INST 2 # advance rPC, load rINST 23 $preinstr # optional op 24 $instr # $result <- op, a0-a3 changed 25 GET_INST_OPCODE v0 # extract opcode from rINST 26 SET_VREG $result, a2 # vA <- $result 27 GOTO_OPCODE v0 # jump to next instruction 28 29
