Re: [Chicken-users] (abs 2147483648) evaluates to negative number
On Fri, Jul 31, 2009 at 8:02 AM, Alejandro Forero
Cuervo wrote:
> In Chicken 3.4.0 linux-unix-gnu-x86-64 the expression (abs 2147483648)
> evaluates to -2147483648 in both csi and a compiled program (negative?
> and positive?, however, seem to work correctly). It evaluated
> correctly in a 32-bits build of the same version.
Please try attached patch.
Jim
Index: runtime.c
===
--- runtime.c (revision 15090)
+++ runtime.c (working copy)
@@ -5382,7 +5382,7 @@
C_regparm C_word C_fcall C_a_i_abs(C_word **a, int c, C_word x)
{
- if(x & C_FIXNUM_BIT) return C_fix(abs(C_unfix(x)));
+ if(x & C_FIXNUM_BIT) return C_fix(labs(C_unfix(x)));
if(C_immediatep(x) || C_block_header(x) != C_FLONUM_TAG)
barf(C_BAD_ARGUMENT_TYPE_ERROR, "abs", x);
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Re: [Chicken-users] (abs 2147483648) evaluates to negative number
John Cowan scripsit: > The bug is still present in 4.1.1, and it's drastic: > > #;1> (abs 2147483648) > -2147483648 > #;2> (abs 2147483649) > 2147483647 > #;3> (abs 2147483650) > 2147483646 > #;4> (abs 4294967296) > 0 Oops, dropped the following: Almost certainly this is happening because the fixnum is being converted to a C int, which is only 32 bits even on 64-bit architectures, at least the ones we support (in the standard LP64 model, ints are 32-bit and only longs and pointers are 64-bit). A fixnum should always be converted to a C long, which will retain full 63-bit precision on 64-bit systems and still provide 31 bits on 32-bit systems. It wouldn't surprise me if there were a fair number of instances of this bug in various parts of Chicken's C code. A question that remains is what to do when calling an existing C routine that expects an int with a fixnum that is too big to fit in 32 bits. Just truncating the fixnum doesn't seem like a Good Thing. -- John Cowan co...@ccil.org http://www.ccil.org/~cowan Most languages are dramatically underdescribed, and at least one is dramatically overdescribed. Still other languages are simultaneously overdescribed and underdescribed. Welsh pertains to the third category. --Alan King ___ Chicken-users mailing list Chicken-users@nongnu.org http://lists.nongnu.org/mailman/listinfo/chicken-users
Re: [Chicken-users] (abs 2147483648) evaluates to negative number
Alejandro Forero Cuervo scripsit: > In Chicken 3.4.0 linux-unix-gnu-x86-64 the expression (abs 2147483648) > evaluates to -2147483648 in both csi and a compiled program (negative? > and positive?, however, seem to work correctly). The bug is still present in 4.1.1, and it's drastic: #;1> (abs 2147483648) -2147483648 #;2> (abs 2147483649) 2147483647 #;3> (abs 2147483650) 2147483646 #;4> (abs 4294967296) 0 > It evaluated correctly in a 32-bits build of the same version. It works in 32-bit Chicken because 2147483648 (like every integer greater than 1073741823) is a flonum. > In the meantime, I'll put the following in my programs. Other people > may want to do the same: > > (when (negative? (abs 2147483648)) > (set! abs > (lambda (x) > (if (negative? x) > (- x) > x I'd just override the definition of abs to begin with. -- John Cowan co...@ccil.org http://www.ccil.org/~cowan Any day you get all five woodpeckers is a good day. --Elliotte Rusty Harold ___ Chicken-users mailing list Chicken-users@nongnu.org http://lists.nongnu.org/mailman/listinfo/chicken-users
[Chicken-users] (abs 2147483648) evaluates to negative number
In Chicken 3.4.0 linux-unix-gnu-x86-64 the expression (abs 2147483648) evaluates to -2147483648 in both csi and a compiled program (negative? and positive?, however, seem to work correctly). It evaluated correctly in a 32-bits build of the same version. Is this a known issue? Has it been fixed in a newer version? Thanks! Alejo. http://azul.freaks-unidos.net/ ___ Chicken-users mailing list Chicken-users@nongnu.org http://lists.nongnu.org/mailman/listinfo/chicken-users
