Question

I was trying to test my code so far, and when compiling a test run I’m getting an error.

Here is my code:

mips_op.h file

#ifndef MIPS_OP_H
#define MIPS_OP_H

typedef enum {
    R, I, J
} op_type;

typedef struct op_instr {
    op_type op_t; // instruction type {R, I, J}
    int opcode : 6; // instruction opcode - 6-bit integer

    // if the instruction type is J
    #if op_t == J

    int address : 26; // address to jump to - 26-bit integer

    #else // if the instruction type is R or I

    int rs : 5; // the output - 5-bit integer
    int rt : 5; // the first operand - 5-bit integer

        #if op_t == R // if instruction type is R

        int rd : 5; // the second operand - 5-bit integer
        int shamt : 5; // the shift amount field - 5-bit integer
        int funct : 6; // the function field

        #endif

        #if op_t == I // if instruction type is R

        int immediate : 16; // the immediate field - 16-bit integer

        #endif

    #endif
};

#endif

and here is main.c file

#include <stdio.h>
#include "mips_op.h"

int main (void) {
    printf("Before instr\n");

    op_instr add;

    printf("After instr\n");

    return 0;
}

and here is the error I’m getting

In file included from main.c:2:0:
mips_op.h:9:10: error: expected ')' before 'op_t'
main.c: In function 'main':
main.c:7:2: error: unknown type name 'op_instr'

What is wrong with my code? Why am I getting this error?

Thanks

EDIT: Fixed the brackets to curly brackets

Answer 1

Replace the “(” in the struct definition to “{“

typedef struct op_instr
**{**
   ...
**}**

EDIT: You may are having this problem

“Basically, there’s a complex interaction between ordinary C preprocessor directives, ordinary C language elements, and the inscrutable innards of the Arduino IDE & compiler chain.

As nearly as I can tell, you can wrap #if whatever around simple declarations and most executable code with impunity, but putting anything more elaborate than that, like a simple typedef struct, inside the conditionals causes bizarre problems.

In fact, just typedef can cause problems, particularly if you attempt to use the ensuing tag in a function declaration. Don’t even think about anything along these lines:”