OpenEuphoria

Re: Problems with C floats

• Posted by irv Feb 01, 2010
• 2291 views

// irv.c  
// build with $ gcc -shared -fPIC -ldl irv3.c -o irv3.so  
#include <stdio.h> 
 
static int a = 12; 
static double b = 34567890; 
static float c = 67.890123; 
 
void test_float(int *foo, double *bar, float *baz){ 
 
	printf( "C in:\n\tfoo: %d\n\tbar: %e\n\tbaz: %f\n\n", *foo,*bar,*baz); 
	printf("C routine changes values & should return \n\t12, \t34567890, \t67.890123\n\n"); 
 
	*foo = a;  
	*bar = b;  
	*baz = c;  
	 
	printf( "C out:\n\tfoo: %d\n\tbar: %e\n\tbaz: %f\n\n", *foo,*bar,*baz); 
}  
 

-- irv3.ex 
include std/dll.e 
include std/memory.e 
include std/convert.e as convert 
 
constant 
        irv = open_dll( "./irv3.so" ), 
        test1 = define_c_proc( irv, "test_float", {C_POINTER,C_POINTER,C_POINTER}), 
        test2 = define_c_proc( irv, "test_float", {C_INT,C_DOUBLE,C_FLOAT}) 
         
atom 
		ptr1 = allocate(4), 
		ptr2 = allocate(8), 
		ptr3 = allocate(8) 
		 
poke(ptr1,convert:int_to_bytes(123)) 
poke(ptr2,convert:atom_to_float64(123456789)) 
poke(ptr3,convert:atom_to_float32(3.14159)) 
 
puts(1,"Eu sends: 123, 123456789, 3.14159 to C routine:\n") 
 
-- change the following to test2, and you get a machine exception: 
c_proc( test1, {ptr1,ptr2,ptr3})  
 
puts(1,"Eu received:\n") 
puts(1,"\tINT:") ? peek(ptr1)  
puts(1,"\tDBL:") ? convert:float64_to_atom(peek({ptr2,8}))  
puts(1,"\tFLT:") ? convert:float32_to_atom(peek({ptr3,4})) 

This is the best I can do without knowing any C. Test 1 successfully passes values both ways. Test 2 crashes every time, no matter what values are sent.