[Mono-dev] ARM9 Soft Float Arithmetic

[jaekim]

I'm developing for a Freescale ARM920T processor and I had to use a similar
hack described in "Arm9 NS9215 floating point troubles by Trevor Ackerman". 
Floating point arithmetic does not work with my system.

This is the hack in method-to-ir.c:

                case OP_R8CONST: {
                    DVal d;
                    
                    // ORIGINAL CODE
                    //d.vald = *(double*)ins->inst_p0;
                    //MONO_EMIT_NEW_I8CONST (cfg, ins->dreg, d.vall);

                    // NEW CODE
                    unsigned char *ucp = (unsigned char *) ins->inst_p0;
                    unsigned char rawval[8];
                    
                    rawval[0] = ucp[4];
                    rawval[1] = ucp[5];
                    rawval[2] = ucp[6];
                    rawval[3] = ucp[7];
                     rawval[4] = ucp[0];
                     rawval[5] = ucp[1];
                    rawval[6] = ucp[2];
                    rawval[7] = ucp[3];

                    d.vald = *(double*)rawval;
                    MONO_EMIT_NEW_I8CONST (cfg, ins->dreg, d.vall);

                    break;
                }
                case OP_R4CONST: {
                    DVal d;

                    // ORIGINAL CODE
                    /* We load the r8 value */
                    //d.vald = *(float*)ins->inst_p0;
                    //MONO_EMIT_NEW_I8CONST (cfg, ins->dreg, d.vall);

                    // NEW CODE
                    unsigned char *ucp = (unsigned char *) ins->inst_p0;
                    unsigned char rawval[4];
                    rawval[0] = ucp[3];
                    rawval[1] = ucp[2];
                    rawval[2] = ucp[1];
                    rawval[3] = ucp[0];
                    d.vald = *(double*)rawval;
                    MONO_EMIT_NEW_I8CONST (cfg, ins->dreg, d.vall);
                    break;
                }

This is the C# test code to test multiply.

Code:

using System;
 
public class HelloWorld
{
    static public void Main ()
    {
        double ftest = 1.1;

        Console.WriteLine ("Hello Mono World");

        if(ftest >= 1.0)
            Console.WriteLine("ftest >= 1.0");
        else
            Console.WriteLine("ftest < 1.0");

        ftest *= -32.52;
    
        if(ftest >= 32.52)
            Console.WriteLine("ftest >= 32.52");
        else
            Console.WriteLine("ftest < 32.52");

        Console.WriteLine("ftest = {0}", ftest);
        
        ftest = ftest * 33.33;

        Console.WriteLine("ftest * 33.33 = {0}", ftest);

        ftest = ftest * -33.33;

        Console.WriteLine("ftest * -33.33 = {0}", ftest);
    }
}

Output:

Hello Mono World
ftest >= 1.0
ftest < 32.52
ftest = 1,1
ftest * 33.33 = 1,1
ftest * -33.33 = 1,1

Jae
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