/*---------------------------------------------------------------------------

 *

 * Ryu floating-point output for single precision.

 *

 * Portions Copyright (c) 2018-2026, PostgreSQL Global Development Group

 *

 * IDENTIFICATION

 *    src/common/f2s.c

 *

 * This is a modification of code taken from github.com/ulfjack/ryu under the

 * terms of the Boost license (not the Apache license). The original copyright

 * notice follows:

 *

 * Copyright 2018 Ulf Adams

 *

 * The contents of this file may be used under the terms of the Apache

 * License, Version 2.0.

 *

 *     (See accompanying file LICENSE-Apache or copy at

 *      http://www.apache.org/licenses/LICENSE-2.0)

 *

 * Alternatively, the contents of this file may be used under the terms of the

 * Boost Software License, Version 1.0.

 *

 *     (See accompanying file LICENSE-Boost or copy at

 *      https://www.boost.org/LICENSE_1_0.txt)

 *

 * Unless required by applicable law or agreed to in writing, this software is

 * distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY

 * KIND, either express or implied.

 *

 *---------------------------------------------------------------------------

 */

#ifndef FRONTEND

#include "postgres.h"

#else

#include "postgres_fe.h"

#endif

#include "common/shortest_dec.h"

#include "digit_table.h"

#include "ryu_common.h"

#define FLOAT_MANTISSA_BITS 23

#define FLOAT_EXPONENT_BITS 8

#define FLOAT_BIAS 127

/*

 * This table is generated (by the upstream) by PrintFloatLookupTable,

 * and modified (by us) to add UINT64CONST.

 */

#define FLOAT_POW5_INV_BITCOUNT 59

static const uint64 FLOAT_POW5_INV_SPLIT[31] = {

  UINT64CONST(576460752303423489), UINT64CONST(461168601842738791), UINT64CONST(368934881474191033), UINT64CONST(295147905179352826),

  UINT64CONST(472236648286964522), UINT64CONST(377789318629571618), UINT64CONST(302231454903657294), UINT64CONST(483570327845851670),

  UINT64CONST(386856262276681336), UINT64CONST(309485009821345069), UINT64CONST(495176015714152110), UINT64CONST(396140812571321688),

  UINT64CONST(316912650057057351), UINT64CONST(507060240091291761), UINT64CONST(405648192073033409), UINT64CONST(324518553658426727),

  UINT64CONST(519229685853482763), UINT64CONST(415383748682786211), UINT64CONST(332306998946228969), UINT64CONST(531691198313966350),

  UINT64CONST(425352958651173080), UINT64CONST(340282366920938464), UINT64CONST(544451787073501542), UINT64CONST(435561429658801234),

  UINT64CONST(348449143727040987), UINT64CONST(557518629963265579), UINT64CONST(446014903970612463), UINT64CONST(356811923176489971),

  UINT64CONST(570899077082383953), UINT64CONST(456719261665907162), UINT64CONST(365375409332725730)

};

#define FLOAT_POW5_BITCOUNT 61

static const uint64 FLOAT_POW5_SPLIT[47] = {

  UINT64CONST(1152921504606846976), UINT64CONST(1441151880758558720), UINT64CONST(1801439850948198400), UINT64CONST(2251799813685248000),

  UINT64CONST(1407374883553280000), UINT64CONST(1759218604441600000), UINT64CONST(2199023255552000000), UINT64CONST(1374389534720000000),

  UINT64CONST(1717986918400000000), UINT64CONST(2147483648000000000), UINT64CONST(1342177280000000000), UINT64CONST(1677721600000000000),

  UINT64CONST(2097152000000000000), UINT64CONST(1310720000000000000), UINT64CONST(1638400000000000000), UINT64CONST(2048000000000000000),

  UINT64CONST(1280000000000000000), UINT64CONST(1600000000000000000), UINT64CONST(2000000000000000000), UINT64CONST(1250000000000000000),

  UINT64CONST(1562500000000000000), UINT64CONST(1953125000000000000), UINT64CONST(1220703125000000000), UINT64CONST(1525878906250000000),

  UINT64CONST(1907348632812500000), UINT64CONST(1192092895507812500), UINT64CONST(1490116119384765625), UINT64CONST(1862645149230957031),

  UINT64CONST(1164153218269348144), UINT64CONST(1455191522836685180), UINT64CONST(1818989403545856475), UINT64CONST(2273736754432320594),

  UINT64CONST(1421085471520200371), UINT64CONST(1776356839400250464), UINT64CONST(2220446049250313080), UINT64CONST(1387778780781445675),

  UINT64CONST(1734723475976807094), UINT64CONST(2168404344971008868), UINT64CONST(1355252715606880542), UINT64CONST(1694065894508600678),

  UINT64CONST(2117582368135750847), UINT64CONST(1323488980084844279), UINT64CONST(1654361225106055349), UINT64CONST(2067951531382569187),

  UINT64CONST(1292469707114105741), UINT64CONST(1615587133892632177), UINT64CONST(2019483917365790221)

};

static inline uint32

pow5Factor(uint32 value)

{

  uint32    count = 0;

  for (;;)

  {

    Assert(value != 0);

    const uint32 q = value / 5;

    const uint32 r = value % 5;

    if (r != 0)

      break;

    value = q;

    ++count;

  }

  return count;

}

/*  Returns true if value is divisible by 5^p. */

static inline bool

multipleOfPowerOf5(const uint32 value, const uint32 p)

{

  return pow5Factor(value) >= p;

}

/*  Returns true if value is divisible by 2^p. */

static inline bool

multipleOfPowerOf2(const uint32 value, const uint32 p)

{

  /* return __builtin_ctz(value) >= p; */

  return (value & ((1u << p) - 1)) == 0;

}

/*

 * It seems to be slightly faster to avoid uint128_t here, although the

 * generated code for uint128_t looks slightly nicer.

 */

static inline uint32

mulShift(const uint32 m, const uint64 factor, const int32 shift)

{

  /*

   * The casts here help MSVC to avoid calls to the __allmul library

   * function.

   */

  const uint32 factorLo = (uint32) (factor);

  const uint32 factorHi = (uint32) (factor >> 32);

  const uint64 bits0 = (uint64) m * factorLo;

  const uint64 bits1 = (uint64) m * factorHi;

  Assert(shift > 32);

#ifdef RYU_32_BIT_PLATFORM

  /*

   * On 32-bit platforms we can avoid a 64-bit shift-right since we only

   * need the upper 32 bits of the result and the shift value is > 32.

   */

  const uint32 bits0Hi = (uint32) (bits0 >> 32);

  uint32    bits1Lo = (uint32) (bits1);

  uint32    bits1Hi = (uint32) (bits1 >> 32);

  bits1Lo += bits0Hi;

  bits1Hi += (bits1Lo < bits0Hi);

  const int32 s = shift - 32;

  return (bits1Hi << (32 - s)) | (bits1Lo >> s);

#else             /* RYU_32_BIT_PLATFORM */

  const uint64 sum = (bits0 >> 32) + bits1;

  const uint64 shiftedSum = sum >> (shift - 32);

  Assert(shiftedSum <= PG_UINT32_MAX);

  return (uint32) shiftedSum;

#endif              /* RYU_32_BIT_PLATFORM */

}

static inline uint32

mulPow5InvDivPow2(const uint32 m, const uint32 q, const int32 j)

{

  return mulShift(m, FLOAT_POW5_INV_SPLIT[q], j);

}

static inline uint32

mulPow5divPow2(const uint32 m, const uint32 i, const int32 j)

{

  return mulShift(m, FLOAT_POW5_SPLIT[i], j);

}

static inline uint32

decimalLength(const uint32 v)

{

  /* Function precondition: v is not a 10-digit number. */

  /* (9 digits are sufficient for round-tripping.) */

  Assert(v < 1000000000);

  if (v >= 100000000)

  {

    return 9;

  }

  if (v >= 10000000)

  {

    return 8;

  }

  if (v >= 1000000)

  {

    return 7;

  }

  if (v >= 100000)

  {

    return 6;

  }

  if (v >= 10000)

  {

    return 5;

  }

  if (v >= 1000)

  {

    return 4;

  }

  if (v >= 100)

  {

    return 3;

  }

  if (v >= 10)

  {

    return 2;

  }

  return 1;

}

/*  A floating decimal representing m * 10^e. */

typedef struct floating_decimal_32

{

  uint32    mantissa;

  int32   exponent;

} floating_decimal_32;

static inline floating_decimal_32

f2d(const uint32 ieeeMantissa, const uint32 ieeeExponent)

{

  int32   e2;

  uint32    m2;

  if (ieeeExponent == 0)

  {

    /* We subtract 2 so that the bounds computation has 2 additional bits. */

    e2 = 1 - FLOAT_BIAS - FLOAT_MANTISSA_BITS - 2;

    m2 = ieeeMantissa;

  }

  else

  {

    e2 = ieeeExponent - FLOAT_BIAS - FLOAT_MANTISSA_BITS - 2;

    m2 = (1u << FLOAT_MANTISSA_BITS) | ieeeMantissa;

  }

#if STRICTLY_SHORTEST

  const bool  even = (m2 & 1) == 0;

  const bool  acceptBounds = even;

#else

  const bool  acceptBounds = false;

#endif

  /* Step 2: Determine the interval of legal decimal representations. */

  const uint32 mv = 4 * m2;

  const uint32 mp = 4 * m2 + 2;

  /* Implicit bool -> int conversion. True is 1, false is 0. */

  const uint32 mmShift = ieeeMantissa != 0 || ieeeExponent <= 1;

  const uint32 mm = 4 * m2 - 1 - mmShift;

  /* Step 3: Convert to a decimal power base using 64-bit arithmetic. */

  uint32    vr,

        vp,

        vm;

  int32   e10;

  bool    vmIsTrailingZeros = false;

  bool    vrIsTrailingZeros = false;

  uint8   lastRemovedDigit = 0;

  if (e2 >= 0)

  {

    const uint32 q = log10Pow2(e2);

    e10 = q;

    const int32 k = FLOAT_POW5_INV_BITCOUNT + pow5bits(q) - 1;

    const int32 i = -e2 + q + k;

    vr = mulPow5InvDivPow2(mv, q, i);

    vp = mulPow5InvDivPow2(mp, q, i);

    vm = mulPow5InvDivPow2(mm, q, i);

    if (q != 0 && (vp - 1) / 10 <= vm / 10)

    {

      /*

       * We need to know one removed digit even if we are not going to

       * loop below. We could use q = X - 1 above, except that would

       * require 33 bits for the result, and we've found that 32-bit

       * arithmetic is faster even on 64-bit machines.

       */

      const int32 l = FLOAT_POW5_INV_BITCOUNT + pow5bits(q - 1) - 1;

      lastRemovedDigit = (uint8) (mulPow5InvDivPow2(mv, q - 1, -e2 + q - 1 + l) % 10);

    }

    if (q <= 9)

    {

      /*

       * The largest power of 5 that fits in 24 bits is 5^10, but q <= 9

       * seems to be safe as well.

       *

       * Only one of mp, mv, and mm can be a multiple of 5, if any.

       */

      if (mv % 5 == 0)

      {

        vrIsTrailingZeros = multipleOfPowerOf5(mv, q);

      }

      else if (acceptBounds)

      {

        vmIsTrailingZeros = multipleOfPowerOf5(mm, q);

      }

      else

      {

        vp -= multipleOfPowerOf5(mp, q);

      }

    }

  }

  else

  {

    const uint32 q = log10Pow5(-e2);

    e10 = q + e2;

    const int32 i = -e2 - q;

    const int32 k = pow5bits(i) - FLOAT_POW5_BITCOUNT;

    int32   j = q - k;

    vr = mulPow5divPow2(mv, i, j);

    vp = mulPow5divPow2(mp, i, j);

    vm = mulPow5divPow2(mm, i, j);

    if (q != 0 && (vp - 1) / 10 <= vm / 10)

    {

      j = q - 1 - (pow5bits(i + 1) - FLOAT_POW5_BITCOUNT);

      lastRemovedDigit = (uint8) (mulPow5divPow2(mv, i + 1, j) % 10);

    }

    if (q <= 1)

    {

      /*

       * {vr,vp,vm} is trailing zeros if {mv,mp,mm} has at least q

       * trailing 0 bits.

       */

      /* mv = 4 * m2, so it always has at least two trailing 0 bits. */

      vrIsTrailingZeros = true;

      if (acceptBounds)

      {

        /*

         * mm = mv - 1 - mmShift, so it has 1 trailing 0 bit iff

         * mmShift == 1.

         */

        vmIsTrailingZeros = mmShift == 1;

      }

      else

      {

        /*

         * mp = mv + 2, so it always has at least one trailing 0 bit.

         */

        --vp;

      }

    }

    else if (q < 31)

    {

      /* TODO(ulfjack):Use a tighter bound here. */

      vrIsTrailingZeros = multipleOfPowerOf2(mv, q - 1);

    }

  }

  /*

   * Step 4: Find the shortest decimal representation in the interval of

   * legal representations.

   */

  uint32    removed = 0;

  uint32    output;

  if (vmIsTrailingZeros || vrIsTrailingZeros)

  {

    /* General case, which happens rarely (~4.0%). */

    while (vp / 10 > vm / 10)

    {

      vmIsTrailingZeros &= vm - (vm / 10) * 10 == 0;

      vrIsTrailingZeros &= lastRemovedDigit == 0;

      lastRemovedDigit = (uint8) (vr % 10);

      vr /= 10;

      vp /= 10;

      vm /= 10;

      ++removed;

    }

    if (vmIsTrailingZeros)

    {

      while (vm % 10 == 0)

      {

        vrIsTrailingZeros &= lastRemovedDigit == 0;

        lastRemovedDigit = (uint8) (vr % 10);

        vr /= 10;

        vp /= 10;

        vm /= 10;

        ++removed;

      }

    }

    if (vrIsTrailingZeros && lastRemovedDigit == 5 && vr % 2 == 0)

    {

      /* Round even if the exact number is .....50..0. */

      lastRemovedDigit = 4;

    }

    /*

     * We need to take vr + 1 if vr is outside bounds or we need to round

     * up.

     */

    output = vr + ((vr == vm && (!acceptBounds || !vmIsTrailingZeros)) || lastRemovedDigit >= 5);

  }

  else

  {

    /*

     * Specialized for the common case (~96.0%). Percentages below are

     * relative to this.

     *

     * Loop iterations below (approximately): 0: 13.6%, 1: 70.7%, 2:

     * 14.1%, 3: 1.39%, 4: 0.14%, 5+: 0.01%

     */

    while (vp / 10 > vm / 10)

    {

      lastRemovedDigit = (uint8) (vr % 10);

      vr /= 10;

      vp /= 10;

      vm /= 10;

      ++removed;

    }

    /*

     * We need to take vr + 1 if vr is outside bounds or we need to round

     * up.

     */

    output = vr + (vr == vm || lastRemovedDigit >= 5);

  }

  const int32 exp = e10 + removed;

  floating_decimal_32 fd;

  fd.exponent = exp;

  fd.mantissa = output;

  return fd;

}

static inline int

to_chars_f(const floating_decimal_32 v, const uint32 olength, char *const result)

{

  /* Step 5: Print the decimal representation. */

  int     index = 0;

  uint32    output = v.mantissa;

  int32   exp = v.exponent;

  /*----

   * On entry, mantissa * 10^exp is the result to be output.

   * Caller has already done the - sign if needed.

   *

   * We want to insert the point somewhere depending on the output length

   * and exponent, which might mean adding zeros:

   *

   *            exp  | format

   *            1+   |  ddddddddd000000

   *            0    |  ddddddddd

   *  -1 .. -len+1   |  dddddddd.d to d.ddddddddd

   *  -len ...       |  0.ddddddddd to 0.000dddddd

   */

  uint32    i = 0;

  int32   nexp = exp + olength;

  if (nexp <= 0)

  {

    /* -nexp is number of 0s to add after '.' */

    Assert(nexp >= -3);

    /* 0.000ddddd */

    index = 2 - nexp;

    /* copy 8 bytes rather than 5 to let compiler optimize */

    memcpy(result, "0.000000", 8);

  }

  else if (exp < 0)

  {

    /*

     * dddd.dddd; leave space at the start and move the '.' in after

     */

    index = 1;

  }

  else

  {

    /*

     * We can save some code later by pre-filling with zeros. We know that

     * there can be no more than 6 output digits in this form, otherwise

     * we would not choose fixed-point output. memset 8 rather than 6

     * bytes to let the compiler optimize it.

     */

    Assert(exp < 6 && exp + olength <= 6);

    memset(result, '0', 8);

  }

  while (output >= 10000)

  {

    const uint32 c = output - 10000 * (output / 10000);

    const uint32 c0 = (c % 100) << 1;

    const uint32 c1 = (c / 100) << 1;

    output /= 10000;

    memcpy(result + index + olength - i - 2, DIGIT_TABLE + c0, 2);

    memcpy(result + index + olength - i - 4, DIGIT_TABLE + c1, 2);

    i += 4;

  }

  if (output >= 100)

  {

    const uint32 c = (output % 100) << 1;

    output /= 100;

    memcpy(result + index + olength - i - 2, DIGIT_TABLE + c, 2);

    i += 2;

  }

  if (output >= 10)

  {

    const uint32 c = output << 1;

    memcpy(result + index + olength - i - 2, DIGIT_TABLE + c, 2);

  }

  else

  {

    result[index] = (char) ('0' + output);

  }

  if (index == 1)

  {

    /*

     * nexp is 1..6 here, representing the number of digits before the

     * point. A value of 7+ is not possible because we switch to

     * scientific notation when the display exponent reaches 6.

     */

    Assert(nexp < 7);

    /* gcc only seems to want to optimize memmove for small 2^n */

    if (nexp & 4)

    {

      memmove(result + index - 1, result + index, 4);

      index += 4;

    }

    if (nexp & 2)

    {

      memmove(result + index - 1, result + index, 2);

      index += 2;

    }

    if (nexp & 1)

    {

      result[index - 1] = result[index];

    }

    result[nexp] = '.';

    index = olength + 1;

  }

  else if (exp >= 0)

  {

    /* we supplied the trailing zeros earlier, now just set the length. */

    index = olength + exp;

  }

  else

  {

    index = olength + (2 - nexp);

  }

  return index;

}

static inline int

to_chars(const floating_decimal_32 v, const bool sign, char *const result)

{

  /* Step 5: Print the decimal representation. */

  int     index = 0;

  uint32    output = v.mantissa;

  uint32    olength = decimalLength(output);

  int32   exp = v.exponent + olength - 1;

  if (sign)

    result[index++] = '-';

  /*

   * The thresholds for fixed-point output are chosen to match printf

   * defaults. Beware that both the code of to_chars_f and the value of

   * FLOAT_SHORTEST_DECIMAL_LEN are sensitive to these thresholds.

   */

  if (exp >= -4 && exp < 6)

    return to_chars_f(v, olength, result + index) + sign;

  /*

   * If v.exponent is exactly 0, we might have reached here via the small

   * integer fast path, in which case v.mantissa might contain trailing

   * (decimal) zeros. For scientific notation we need to move these zeros

   * into the exponent. (For fixed point this doesn't matter, which is why

   * we do this here rather than above.)

   *

   * Since we already calculated the display exponent (exp) above based on

   * the old decimal length, that value does not change here. Instead, we

   * just reduce the display length for each digit removed.

   *

   * If we didn't get here via the fast path, the raw exponent will not

   * usually be 0, and there will be no trailing zeros, so we pay no more

   * than one div10/multiply extra cost. We claw back half of that by

   * checking for divisibility by 2 before dividing by 10.

   */

  if (v.exponent == 0)

  {

    while ((output & 1) == 0)

    {

      const uint32 q = output / 10;

      const uint32 r = output - 10 * q;

      if (r != 0)

        break;

      output = q;

      --olength;

    }

  }

  /*----

   * Print the decimal digits.

   * The following code is equivalent to:

   *

   * for (uint32 i = 0; i < olength - 1; ++i) {

   *   const uint32 c = output % 10; output /= 10;

   *   result[index + olength - i] = (char) ('0' + c);

   * }

   * result[index] = '0' + output % 10;

   */

  uint32    i = 0;

  while (output >= 10000)

  {

    const uint32 c = output - 10000 * (output / 10000);

    const uint32 c0 = (c % 100) << 1;

    const uint32 c1 = (c / 100) << 1;

    output /= 10000;

    memcpy(result + index + olength - i - 1, DIGIT_TABLE + c0, 2);

    memcpy(result + index + olength - i - 3, DIGIT_TABLE + c1, 2);

    i += 4;

  }

  if (output >= 100)

  {

    const uint32 c = (output % 100) << 1;

    output /= 100;

    memcpy(result + index + olength - i - 1, DIGIT_TABLE + c, 2);

    i += 2;

  }

  if (output >= 10)

  {

    const uint32 c = output << 1;

    /*

     * We can't use memcpy here: the decimal dot goes between these two

     * digits.

     */

    result[index + olength - i] = DIGIT_TABLE[c + 1];

    result[index] = DIGIT_TABLE[c];

  }

  else

  {

    result[index] = (char) ('0' + output);

  }

  /* Print decimal point if needed. */

  if (olength > 1)

  {

    result[index + 1] = '.';

    index += olength + 1;

  }

  else

  {

    ++index;

  }

  /* Print the exponent. */

  result[index++] = 'e';

  if (exp < 0)

  {

    result[index++] = '-';

    exp = -exp;

  }

  else

    result[index++] = '+';

  memcpy(result + index, DIGIT_TABLE + 2 * exp, 2);

  index += 2;

  return index;

}

static inline bool

f2d_small_int(const uint32 ieeeMantissa,

        const uint32 ieeeExponent,

        floating_decimal_32 *v)

{

  const int32 e2 = (int32) ieeeExponent - FLOAT_BIAS - FLOAT_MANTISSA_BITS;

  /*

   * Avoid using multiple "return false;" here since it tends to provoke the

   * compiler into inlining multiple copies of f2d, which is undesirable.

   */

  if (e2 >= -FLOAT_MANTISSA_BITS && e2 <= 0)

  {

    /*----

     * Since 2^23 <= m2 < 2^24 and 0 <= -e2 <= 23:

     *   1 <= f = m2 / 2^-e2 < 2^24.

     *

     * Test if the lower -e2 bits of the significand are 0, i.e. whether

     * the fraction is 0. We can use ieeeMantissa here, since the implied

     * 1 bit can never be tested by this; the implied 1 can only be part

     * of a fraction if e2 < -FLOAT_MANTISSA_BITS which we already

     * checked. (e.g. 0.5 gives ieeeMantissa == 0 and e2 == -24)

     */

    const uint32 mask = (1U << -e2) - 1;

    const uint32 fraction = ieeeMantissa & mask;

    if (fraction == 0)

    {

      /*----

       * f is an integer in the range [1, 2^24).

       * Note: mantissa might contain trailing (decimal) 0's.

       * Note: since 2^24 < 10^9, there is no need to adjust

       * decimalLength().

       */

      const uint32 m2 = (1U << FLOAT_MANTISSA_BITS) | ieeeMantissa;

      v->mantissa = m2 >> -e2;

      v->exponent = 0;

      return true;

    }

  }

  return false;

}

/*

 * Store the shortest decimal representation of the given float as an

 * UNTERMINATED string in the caller's supplied buffer (which must be at least

 * FLOAT_SHORTEST_DECIMAL_LEN-1 bytes long).

 *

 * Returns the number of bytes stored.

 */

int

float_to_shortest_decimal_bufn(float f, char *result)

{

  /*

   * Step 1: Decode the floating-point number, and unify normalized and

   * subnormal cases.

   */

  const uint32 bits = float_to_bits(f);

  /* Decode bits into sign, mantissa, and exponent. */

  const bool  ieeeSign = ((bits >> (FLOAT_MANTISSA_BITS + FLOAT_EXPONENT_BITS)) & 1) != 0;

  const uint32 ieeeMantissa = bits & ((1u << FLOAT_MANTISSA_BITS) - 1);

  const uint32 ieeeExponent = (bits >> FLOAT_MANTISSA_BITS) & ((1u << FLOAT_EXPONENT_BITS) - 1);

  /* Case distinction; exit early for the easy cases. */

  if (ieeeExponent == ((1u << FLOAT_EXPONENT_BITS) - 1u) || (ieeeExponent == 0 && ieeeMantissa == 0))

  {

    return copy_special_str(result, ieeeSign, (ieeeExponent != 0), (ieeeMantissa != 0));

  }

  floating_decimal_32 v;

  const bool  isSmallInt = f2d_small_int(ieeeMantissa, ieeeExponent, &v);

  if (!isSmallInt)

  {

    v = f2d(ieeeMantissa, ieeeExponent);

  }

  return to_chars(v, ieeeSign, result);

}

/*

 * Store the shortest decimal representation of the given float as a

 * null-terminated string in the caller's supplied buffer (which must be at

 * least FLOAT_SHORTEST_DECIMAL_LEN bytes long).

 *

 * Returns the string length.

 */

int

float_to_shortest_decimal_buf(float f, char *result)

{

  const int index = float_to_shortest_decimal_bufn(f, result);

  /* Terminate the string. */

  Assert(index < FLOAT_SHORTEST_DECIMAL_LEN);

  result[index] = '\0';

  return index;

}

/*

 * Return the shortest decimal representation as a null-terminated palloc'd

 * string (outside the backend, uses malloc() instead).

 *

 * Caller is responsible for freeing the result.

 */

char *

float_to_shortest_decimal(float f)

{

  char     *const result = (char *) palloc(FLOAT_SHORTEST_DECIMAL_LEN);

  float_to_shortest_decimal_buf(f, result);

  return result;

}