On 01/02/2024 12:43, Rozenberg, Eyal (Consultant) wrote:
If I try to use the od utility to print half-precision (FP16) floating-point
values, I get:
$ od -t f2 myfloats.bin
od: invalid type string 'f2';
this system doesn't provide a 2-byte floating point type
I'm not exactly sure what "this system" means, but that should work and print
out my floats.
Eyal
PS - This is my first bug-coreutils post, please be gentle.
I just had a read of these:
https://gcc.gnu.org/onlinedocs/gcc/Half-Precision.html
https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p0192r4.html
On the face of it it seems that various 16 bit floating point formats have
consolidated,
and we could add support for _Float16 in od.
I see gnulib already enables __STDC_WANT_IEC_60559_TYPES_EXT__
so we should be able to do something like the attached.
This is just off the top of my head, and I haven't tested
or thought about this much at all.
Any testing your could do would be appreciated.
thanks,
Pádraig
commit 82fc25ab7f34a8198a8f435c1396801d30e8c6b6
Author: Pádraig Brady <p...@draigbrady.com>
Date: Thu Feb 1 17:59:51 2024 +0000
od: support half precision floating point
* src/od.c: Suport -t f2 to print 16 bit floating point.
* NEWS: Mention the new feature.
Addresses https://bugs.gnu.org/68871
diff --git a/src/od.c b/src/od.c
index 75bed5e7d..2f03a729e 100644
--- a/src/od.c
+++ b/src/od.c
@@ -19,6 +19,7 @@
#include <config.h>
#include <ctype.h>
+#include <float.h>
#include <stdio.h>
#include <getopt.h>
#include <sys/types.h>
@@ -49,6 +50,12 @@ typedef unsigned long long int unsigned_long_long_int;
typedef unsigned long int unsigned_long_long_int;
#endif
+#ifndef FLT16_MAX
+/* This is just a place-holder to avoid a few '#if' directives.
+ In this case, the type isn't actually used. */
+typedef float _Float16;
+#endif
+
enum size_spec
{
NO_SIZE,
@@ -58,6 +65,7 @@ enum size_spec
LONG,
LONG_LONG,
/* FIXME: add INTMAX support, too */
+ FLOAT_HALF,
FLOAT_SINGLE,
FLOAT_DOUBLE,
FLOAT_LONG_DOUBLE,
@@ -156,6 +164,7 @@ static const int width_bytes[] =
sizeof (int),
sizeof (long int),
sizeof (unsigned_long_long_int),
+ sizeof (_Float16),
sizeof (float),
sizeof (double),
sizeof (long double)
@@ -477,6 +486,7 @@ PRINT_TYPE (print_int, unsigned int)
PRINT_TYPE (print_long, unsigned long int)
PRINT_TYPE (print_long_long, unsigned_long_long_int)
+PRINT_FLOATTYPE (print_halffloat, _Float16, ftoastr, FLT_BUFSIZE_BOUND)
PRINT_FLOATTYPE (print_float, float, ftoastr, FLT_BUFSIZE_BOUND)
PRINT_FLOATTYPE (print_double, double, dtoastr, DBL_BUFSIZE_BOUND)
PRINT_FLOATTYPE (print_long_double, long double, ldtoastr, LDBL_BUFSIZE_BOUND)
@@ -824,6 +834,11 @@ decode_one_format (char const *s_orig, char const *s, char const **next,
switch (size_spec)
{
+ case FLOAT_HALF:
+ print_function = print_halffloat;
+ field_width = FLT_STRLEN_BOUND_L (decimal_point_len);
+ break;
+
case FLOAT_SINGLE:
print_function = print_float;
field_width = FLT_STRLEN_BOUND_L (decimal_point_len);
@@ -1598,6 +1613,9 @@ main (int argc, char **argv)
for (i = 0; i <= MAX_FP_TYPE_SIZE; i++)
fp_type_size[i] = NO_SIZE;
+#ifdef FLT16_MAX
+ fp_type_size[sizeof (_Float16)] = FLOAT_HALF;
+#endif
fp_type_size[sizeof (float)] = FLOAT_SINGLE;
/* The array entry for 'double' is filled in after that for 'long double'
so that if they are the same size, we avoid any overhead of
