File:  [The Machine Emulator] / tme / generic / float-auto.sh
Revision 1.1.1.2 (vendor branch): download - view: text, annotated - select for diffs
Tue Apr 24 16:41:14 2018 UTC (3 years, 9 months ago) by root
Branches: heeltoe, fredette, MAIN
CVS tags: tme-0_8heeltoe, tme-0_8, tme-0_6, HEAD
tme-0.6

#! /bin/sh

# $Id: float-auto.sh,v 1.1.1.2 2018-04-24 16:41:14 root Exp $

# generic/float-auto.sh - automatically generates C code for floating
# point conversion functions:

#
# Copyright (c) 2004 Matt Fredette
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
# 1. Redistributions of source code must retain the above copyright
#    notice, this list of conditions and the following disclaimer.
# 2. Redistributions in binary form must reproduce the above copyright
#    notice, this list of conditions and the following disclaimer in the
#    documentation and/or other materials provided with the distribution.
# 3. All advertising materials mentioning features or use of this software
#    must display the following acknowledgement:
#      This product includes software developed by Matt Fredette.
# 4. The name of the author may not be used to endorse or promote products
#    derived from this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
# IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
# WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
# DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
# INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
# (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
# SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
# HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
# STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
# ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.
#

header=false
for option
do
    case $option in
    --header) header=true ;;
    esac
done

PROG=`basename $0`
cat <<EOF
/* automatically generated by $PROG, do not edit! */

EOF
if $header; then :; else
    cat <<EOF
#include <tme/common.h>
_TME_RCSID("\$Id: float-auto.sh,v 1.1.1.2 2018-04-24 16:41:14 root Exp $");

/* includes: */
#include <tme/generic/float.h>

EOF
fi

# permute over the builtin types:
#
for _builtin_type in float double long_double; do

    # make the builtin type without underscores, and in all caps:
    #
    builtin_type=`echo ${_builtin_type} | sed -e 's/_/ /g'`
    _BUILTIN_TYPE=`echo ${_builtin_type} | tr 'a-z' 'A-Z'`

    # dispatch on the builtin type to open any protection:
    #
    case ${_builtin_type} in
    long_double) 
	echo ; echo "#ifdef _TME_HAVE_${_BUILTIN_TYPE}" ;;
    *) ;;
    esac

    # if we're generating a header:
    #
    if $header; then
	cat <<EOF

/* if possible, this returns a positive or negative infinity
   ${builtin_type}, otherwise, this returns the ${builtin_type} value
   closest to that infinity: */
${builtin_type} tme_float_infinity_${_builtin_type} _TME_P((int));

/* if possible, this returns a negative zero ${builtin_type}.
   otherwise, this returns the negative ${builtin_type} value closest
   to zero: */
${builtin_type} tme_float_negative_zero_${_builtin_type} _TME_P((void));
EOF
    else
	cat <<EOF

/* if possible, this returns a positive or negative infinity
   ${builtin_type}, otherwise, this returns the ${builtin_type} value
   closest to that infinity: */
${builtin_type}
tme_float_infinity_${_builtin_type}(int negative)
{
  static int inf_set_${_builtin_type};
  static ${builtin_type} inf_${_builtin_type}[2];
  ${builtin_type} inf_test;
  int negative_i;

  /* make sure that negative can index the inf_${_builtin_type} array: */
  negative = !!negative;

  /* if the ${builtin_type} infinities have already been set: */
  if (__tme_predict_true(inf_set_${_builtin_type})) {
    return (inf_${_builtin_type}[negative]);
  }

  /* the ${builtin_type} infinities will be set now: */
  inf_set_${_builtin_type} = TRUE;

  /* set the positive and negative infinities: */
  for (negative_i = 0; negative_i < 2; negative_i++) {

    /* start with the limit maximum positive value or limit minimum
       negative value.  double this value until either it doesn't
       change or it isn't closer to the desired infinity, and then
       use the previous value: */
    inf_test = FLOAT_MAX_${_BUILTIN_TYPE};
    if (negative_i) {
      inf_test = -inf_test;
    }
    do {
      memcpy((char *) &inf_${_builtin_type}[negative_i], (char *) &inf_test, sizeof(inf_test));
      inf_test *= 2;
    } while (memcmp((char *) &inf_${_builtin_type}[negative_i], (char *) &inf_test, sizeof(inf_test)) != 0
             && (negative_i
                 ? inf_test < inf_${_builtin_type}[negative_i]
                 : inf_test > inf_${_builtin_type}[negative_i]));

    /* try to generate the actual infinity by dividing one or negative
       one by zero.  if this value is closer to the desired infinity,
       use it: */
    inf_test = (negative_i ? -1.0 : 1.0) / 0.0;
    if (negative_i
        ? inf_test < inf_${_builtin_type}[negative_i]
        : inf_test > inf_${_builtin_type}[negative_i]) {
      inf_${_builtin_type}[negative_i] = inf_test;
    }
  }

  /* return the desired infinity: */
  return (inf_${_builtin_type}[negative]);
}

/* if possible, this returns a negative zero ${builtin_type}.
   otherwise, this returns the negative ${builtin_type} value closest
   to zero: */
${builtin_type}
tme_float_negative_zero_${_builtin_type}(void)
{
  static int nzero_set_${_builtin_type};
  static ${builtin_type} nzero_${_builtin_type};
  ${builtin_type} constant_pzero;
  ${builtin_type} constant_nzero;
  ${builtin_type} nzero_test;

  /* if the ${builtin_type} negative zero has already been set: */
  if (__tme_predict_true(nzero_set_${_builtin_type})) {
    return (nzero_${_builtin_type});
  }

  /* the ${builtin_type} negative zero will be set now: */
  nzero_set_${_builtin_type} = TRUE;

  /* make a +0.0 and a -0.0, that we can do bit-for-bit comparisons with.
     NB that sizeof(${builtin_type}) may cover more bits than are actually 
     used by a ${builtin_type}: */
  memset((char *) &constant_pzero, 0, sizeof(constant_pzero));
  memset((char *) &constant_nzero, 0, sizeof(constant_nzero));
  constant_pzero = +0.0;
  constant_nzero = -0.0;

  /* if -0.0 * -0.0 is bit-for-bit different from -0.0 and is
     bit-for-bit identical to +0.0, use -0.0: */
  memset((char *) &nzero_test, 0, sizeof(nzero_test));
  nzero_test = constant_nzero * constant_nzero;
  if (memcmp((char *) &constant_nzero, (char *) &nzero_test, sizeof(nzero_test)) != 0
      && memcmp((char *) &constant_pzero, (char *) &nzero_test, sizeof(nzero_test)) == 0) {
    return (nzero_${_builtin_type} = constant_nzero);
  }

  /* otherwise, start with the limit maximum negative value (which is
     zero minus the limit minimum positive value).  halve this value
     until either it doesn't change or it becomes positive zero, and
     then use the previous value: */
  nzero_test = 0 - FLOAT_MIN_${_BUILTIN_TYPE};
  do {
    memcpy((char *) &nzero_${_builtin_type}, (char *) &nzero_test, sizeof(nzero_test));
    nzero_test = nzero_test / 2;
  } while (memcmp((char *) &nzero_${_builtin_type}, (char *) &nzero_test, sizeof(nzero_test)) != 0
	   && memcmp((char *) &constant_pzero, (char *) &nzero_test, sizeof(nzero_test)) != 0);
  return (nzero_${_builtin_type});
}
EOF
    fi


    # permute over the radices:
    #
    for radix in 2 10; do

	# if we're generating a header:
	#
	if $header; then
	    cat <<EOF

/* this returns the radix ${radix} mantissa and exponent of an in-range ${builtin_type}.
   the mantissa is either zero, or in the range [1,${radix}): */
${builtin_type} tme_float_radix${radix}_mantissa_exponent_${_builtin_type} _TME_P((${builtin_type}, tme_int32_t *));

/* this scales a value by adding n to its radix ${radix} exponent: */
${builtin_type} tme_float_radix${radix}_scale_${_builtin_type} _TME_P((${builtin_type}, tme_int32_t));
EOF
	    continue
	fi

	# permute over the sign of the exponent:
	#
	for _sign in pos neg; do

	    # make the sign into two operators:
	    #
	    if test ${_sign} = pos; then sign= ; combine='*' ; else sign=- ; combine='/' ; fi

	    echo ""
	    echo "/* a series of ${builtin_type} values of the form ${radix}^${sign}x, where x is a power of two: */"
	    echo "static const ${builtin_type} _tme_float_radix${radix}_exponent_bits_${_builtin_type}_${_sign}[] = {"
	    exponent=1
	    formats_last=

	    while true; do

		# dispatch on the radix to get the largest factor we will
		# use, its exponent, and a coarse upper bound on this
		# value's exponent in the worst-case radix of two:
		#
		case ${radix} in
		2)  exponent_radix2=${exponent} ; x=16777216 ; exponent_x=24 ;;
		10) exponent_radix2=`expr ${exponent} \* 4` ; x=10000 ; exponent_x=4 ;;
		*) 
		    echo "$PROG internal error: can't handle radix ${radix}" 1>&2 
		    exit 1
		    ;;
		esac

		# we assume that all floating-point formats that use a
		# radix of two support at least positive and negative
		# exponents of magnitude 16.  if this exponent's
		# magnitude is greater than that, dispatch to get the
		# list of floating-point formats that support it:
		#
		formats=
		if test `expr ${exponent_radix2} \> 16` != 0; then

		    # the IEEE 754 types:
		    #
		    if test `expr ${exponent_radix2} \< 16384` != 0; then
			formats="${formats} | TME_FLOAT_FORMAT_IEEE754_EXTENDED80"
		    fi
		    if test `expr ${exponent_radix2} \< 1024` != 0; then
			formats="${formats} | TME_FLOAT_FORMAT_IEEE754_DOUBLE"
		    fi
		    if test `expr ${exponent_radix2} \< 128` != 0; then
			formats="${formats} | TME_FLOAT_FORMAT_IEEE754_SINGLE"
		    fi

		    # if we don't know any formats that support this
		    # exponent, stop now:
		    #
		    if test "x${formats}" = x; then
			break
		    fi

		    # clean up the formats:
		    #
		    formats="((TME_FLOAT_FORMAT_${_BUILTIN_TYPE} & ("`echo "${formats}" | sed -e 's%^ | %%'`")) != 0)"
		fi

		# if the formats have changed: 
		#
		if test "x${formats}" != "x${formats_last}"; then

		    # close any old #if first:
		    #
		    if test "x${formats_last}" != x; then
			echo ""
			echo "#endif /* ${formats_last} */"
		    fi

		    # open the new #if:
		    #
		    echo ""
		    echo "#if ${formats}"
		    formats_last=${formats}
		fi

		# compute this value:
		#
		echo ""
		echo "  /* ${radix}^${sign}${exponent}: */"
		exponent_remaining=${exponent}
		value=1
		while test ${exponent_remaining} != 0; do
		    if test `expr ${exponent_remaining} \>= ${exponent_x}` = 1; then
			value="(${value} ${combine} ((${builtin_type}) ((tme_uint32_t) ${x})))"
			exponent_remaining=`expr ${exponent_remaining} - ${exponent_x}`
		    else
			x=`expr ${x} / ${radix}`
			exponent_x=`expr ${exponent_x} - 1`
		    fi
		done
		echo "  ${value},"

		# double the exponent:
		#
		exponent=`expr ${exponent} \* 2`
	    done

	    # close any #if:
	    #
	    if test "x${formats_last}" != x; then
		echo ""
		echo "#endif /* ${formats_last} */"
	    fi

	    echo "};"
	done

cat <<EOF

/* this returns the radix ${radix} mantissa and exponent of an in-range ${builtin_type}.
   the mantissa is either zero, or in the range [1,${radix}): */
${builtin_type}
tme_float_radix${radix}_mantissa_exponent_${_builtin_type}(${builtin_type} value, tme_int32_t *_exponent)
{
  tme_int32_t exponent;
  tme_uint32_t exponent_bit;
  int negate;

  /* start with an exponent of zero: */
  exponent = 0;

  /* if the value is positive or negative zero, return the value: */
  if (value == 0.0
      || -value == 0.0) {
    *_exponent = exponent;
    return (value);
  }

  /* take the magnitude of the value, but remember if it was negative: */
  negate = (value < 0);
  if (negate) {
    value = 0 - value;
  }

  /* while the value is less than one: */
  exponent_bit = TME_ARRAY_ELS(_tme_float_radix${radix}_exponent_bits_${_builtin_type}_neg) - 1;
  for (; value < 1; ) {

    /* if value is less than or equal to ${radix}^-(2^exponent_bit),
       divide value by ${radix}^-(2^exponent_bit), and subtract 2^exponent_bit
       from exponent: */
    if (value <= _tme_float_radix${radix}_exponent_bits_${_builtin_type}_neg[exponent_bit]
        || exponent_bit == 0) {
      value /= _tme_float_radix${radix}_exponent_bits_${_builtin_type}_neg[exponent_bit];
      exponent -= (1 << exponent_bit);
    }

    /* otherwise, move to the next exponent bit: */
    else {
      exponent_bit--;
    }
  }

  /* while the value is greater than or equal to ${radix}: */
  exponent_bit = TME_ARRAY_ELS(_tme_float_radix${radix}_exponent_bits_${_builtin_type}_pos) - 1;
  for (; value >= ${radix}; ) {

    /* if value is greater than or equal to ${radix}^(2^exponent_bit),
       divide value by ${radix}^(2^exponent_bit), and add 2^exponent_bit
       to exponent: */
    if (value >= _tme_float_radix${radix}_exponent_bits_${_builtin_type}_pos[exponent_bit]
        || exponent_bit == 0) {
      value /= _tme_float_radix${radix}_exponent_bits_${_builtin_type}_pos[exponent_bit];
      exponent += (1 << exponent_bit);
    }

    /* otherwise, move to the next exponent bit: */
    else {
      exponent_bit--;
    }
  }

  /* done: */
  *_exponent = exponent;
  return (negate ? 0 - value : value);
}

/* this scales a value by adding n to its exponent: */
${builtin_type}
tme_float_radix${radix}_scale_${_builtin_type}(${builtin_type} value, tme_int32_t _n)
{
  tme_uint32_t exponent_bit, exponent;
  tme_uint32_t n;

  /* start with the most significant exponent bit: */
  exponent_bit = TME_ARRAY_ELS(_tme_float_radix${radix}_exponent_bits_${_builtin_type}_pos) - 1;
  exponent = (1 << exponent_bit);

  /* if n is negative: */
  if (_n < 0) {

    for (n = 0 - _n; n > 0;) {
      if (n >= exponent || exponent == 1) {
        value /= _tme_float_radix${radix}_exponent_bits_${_builtin_type}_pos[exponent_bit];
        n -= exponent;
      }
      else {
        exponent >>= 1;
        exponent_bit--;
      }
    }
  }

  /* otherwise, n is positive: */
  else {
    for (n = _n; n > 0;) {
      if (n >= exponent || exponent == 1) {
        value *= _tme_float_radix${radix}_exponent_bits_${_builtin_type}_pos[exponent_bit];
        n -= exponent;
      }
      else {
        exponent >>= 1;
        exponent_bit--;
      }
    }
  }

  return (value);
}
EOF
    done

    # dispatch on the type to close any protection:
    #
    case ${_builtin_type} in
    long_double) 
	echo ; echo "#endif /* _TME_HAVE_${_BUILTIN_TYPE} */" ;;
    *) ;;
    esac

done
	
# done:
#
exit 0

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