OpenEuphoria

Re: Problems with C floats

• Posted by mattlewis (admin) Jan 31, 2010
• 2379 views

I updated my test to:

// irv.c 
// build with $ gcc -shared -fPIC -ldl irv.c -o irv.so 
#include <stdio.h> 
 
void test_float( float foo, double bar, int baz ){ 
	printf( "double: %e\nfloat: %e\nint: %d\n", foo, bar, baz ); 
} 
 
float test_irv( int *ptr, float f1, float f2, float f3, int i ){ 
	printf( "ptr: %p\nf1: %f (%x)\nf2: %f (%x)\nf3: %f (%x)\ni: %d\n", 
			ptr,  
			f1, *(int*)(&f1), 
			f2, *(int*)(&f2), 
			f3, *(int*)(&f3), 
			i ); 
	return f1 + f2; 
} 

...and...

-- irv.ex 
include std/dll.e 
 
constant 
	irv = open_dll( "./irv.so" ), 
	test_float = define_c_proc( irv, "test_float", {C_FLOAT, C_DOUBLE, C_INT}), 
	test_irv   = define_c_func( irv, "test_irv", {C_POINTER, C_FLOAT, C_FLOAT, C_FLOAT, C_INT}, C_FLOAT ) 
 
c_proc( test_float, { 0.25, 0.75, 9}) 
? c_func( test_irv, { 0xDEADBEEF, 1.1, 2.3, 0.5, 8008135} ) 

And I get:

$ eui irv 
double: 2.500000e-01 
float: 7.500000e-01 
int: 9 
ptr: 0xdeadbeef 
f1: 1.100000 (3f8ccccd) 
f2: 2.300000 (40133333) 
f3: 0.500000 (3f000000) 
i: 8008135 
3.399999976 

Or did you mean as a callback? That shouldn't have ever worked. A euphoria callback routine assumes that it's getting back all 32-bit integers, so you'd need to convert the float:

function my_callback( atom the_float ) 
    poke4( buffer, the_float ) 
    the_float = float32_to_atom( peek( { buffer, 4 } ) ) 
    return 0 
end function 

Matt