Assembly language parse error before '[' token

Question

I get a parse error on line 24(I believe) "parse error before '[' token"

Also, if any of you would like to give me some helpful tips and insights into my project I would appreciate that very much. I'm building a pow function with all calculations done in asm, this piece of code is to change the FPU to round to 0 so that I can split up the exponent into 2 parts (example: 2^3.2 = 2^3 * 2^0.2)

#include <stdio.h>
#include <stdlib.h>

#define PRECISION           3
#define RND_CTL_BIT_SHIFT   10

// floating point rounding modes: IA-32 Manual, Vol. 1, p. 4-20
typedef enum {
    ROUND_TOWARD_ZERO =     3 << RND_CTL_BIT_SHIFT
} RoundingMode;

int main(int argc, char **argv)
{

        int fpMask      = 0x1F9FF;
        int localVar    = 0x00000;

        asm("           FSTCW           %[localVarIn]                   \n" // store FPU control word into localVar
            "           add             %[localVarIn], %[fpMaskOut]     \n" // add fpMaskIn to localVar

        :   [localVarOut]   "=m"    (localVar)
        :   [fpMaskOut]     "=m"    (fpMask)

        :   [localVarIn]    "m"     (localVar)
        :   [fpMaskIn]      "m"     (localVar)
    );

    printf("FPU is 0x%08X\n\n", localVar);

return 0;

}

Answer 1

I believe your clobber list is slightly wrong. In GCC, these take the form of the following:

asm("MY ASM CODE" : output0, output1, outputn 
                  : input0, input1, inputn 
                  : clobber0, clobber1, clobbern);

Note that each class is colon-separated (i.e. the set of outputs, the set of inputs etc), then each element within a set is comma-separated. Therefore, try changing your ASM to the following:

asm("           FSTCW           %[localVarIn]                   \n" // store FPU control word into localVar
    "           add             %[localVarIn], %[fpMaskOut]     \n" // add fpMaskIn to localVar

    :   [localVarOut]   "=m"    (localVar),         // Outputs...
        [fpMaskOut]     "=m"    (fpMask)

    :   [localVarIn]    "m"     (localVar),         // Inputs...
        [fpMaskIn]      "m"     (localVar)