Example: Decompressing raw data

[jhunkeler]

Reference-only

[jhunkeler]

[ 15%] Building C object examples/CMakeFiles/asdf_dump_ndarray.dir/__/src/core/ndarray_convert.c.o
In file included from /Users/runner/work/libasdf/libasdf/src/core/ndarray_convert.c:9:
/Library/Developer/CommandLineTools/SDKs/MacOSX14.sdk/usr/include/math.h:54:5: error: #error "Unsupported value of __FLT_EVAL_METHOD__."
   54 | #   error "Unsupported value of __FLT_EVAL_METHOD__."
      |     ^~~~~
make[2]: *** [examples/CMakeFiles/asdf_dump_ndarray.dir/__/src/core/ndarray_convert.c.o] Error 1
make[1]: *** [examples/CMakeFiles/asdf_dump_ndarray.dir/all] Error 2
make: *** [all] Error 2

Always something ™️

[jhunkeler]

float.h

    73  /* Characteristics of floating point types, C99 5.2.4.2.2 */
    74
    75  #define FLT_EVAL_METHOD __FLT_EVAL_METHOD__

math.h

    36  /******************************************************************************
    37   * Floating point data types                                                  *
    38   ******************************************************************************/
    39
    40  /*  Define float_t and double_t per C standard, ISO/IEC 9899:2011 7.12 2,
    41      taking advantage of GCC's __FLT_EVAL_METHOD__ (which a compiler may
    42      define anytime and GCC does) that shadows FLT_EVAL_METHOD (which a
    43      compiler must define only in float.h).                                    */
    44  #if __FLT_EVAL_METHOD__ == 0 || __FLT_EVAL_METHOD__ == -1
    45      typedef float float_t;
    46      typedef double double_t;
    47  #elif __FLT_EVAL_METHOD__ == 1
    48      typedef double float_t;
    49      typedef double double_t;
    50  #elif __FLT_EVAL_METHOD__ == 2
    51      typedef long double float_t;
    52      typedef long double double_t;
    53  #else /* __FLT_EVAL_METHOD__ */
    54  #   error "Unsupported value of __FLT_EVAL_METHOD__."
    55  #endif /* __FLT_EVAL_METHOD__ */

Test case

$ sw_vers
ProductName:            macOS
ProductVersion:         14.7.6
BuildVersion:   

$ uname -m
arm64

flt_eval_method.c

#include <float.h>
#include <math.h>
#include <stdio.h>

int main(int argc, char *argv[]) {
        printf("__FLT_EVAL_METHOD__ = %d\n", __FLT_EVAL_METHOD__);
        return 0;
}

clang

$ clang flt_eval_method.c && ./a.out
__FLT_EVAL_METHOD__ = 0

gcc 13

$ gcc-13 flt_eval_method.c && ./a.out
__FLT_EVAL_METHOD__ = 0

gcc 14

$ gcc-14 flt_eval_method.c && ./a.out
__FLT_EVAL_METHOD__ = 16

[embray]

This looks like a pretty useful utility to build into the CLI.