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printf-frexp.c #1

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/home/opencoverage/opencoverage/guest-scripts/coreutils/src/gnulib/lib/printf-frexp.c

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1 /* Split a double into fraction and mantissa, for hexadecimal printf. -

3 -

4 This program is free software: you can redistribute it and/or modify -

5 it under the terms of the GNU General Public License as published by -

6 the Free Software Foundation; either version 3 of the License, or -

7 (at your option) any later version. -

8 -

9 This program is distributed in the hope that it will be useful, -

10 but WITHOUT ANY WARRANTY; without even the implied warranty of -

11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the -

12 GNU General Public License for more details. -

13 -

14 You should have received a copy of the GNU General Public License -

15 along with this program. If not, see <https://www.gnu.org/licenses/>. */ -

16 -

17 #if ! defined USE_LONG_DOUBLE -

18 # include <config.h> -

19 #endif -

20 -

21 /* Specification. */ -

22 #ifdef USE_LONG_DOUBLE -

23 # include "printf-frexpl.h" -

24 #else -

25 # include "printf-frexp.h" -

26 #endif -

27 -

28 #include <float.h> -

29 #include <math.h> -

30 #ifdef USE_LONG_DOUBLE -

31 # include "fpucw.h" -

32 #endif -

33 -

34 /* This file assumes FLT_RADIX = 2. If FLT_RADIX is a power of 2 greater -

35 than 2, or not even a power of 2, some rounding errors can occur, so that -

36 then the returned mantissa is only guaranteed to be <= 2.0, not < 2.0. */ -

37 -

38 #ifdef USE_LONG_DOUBLE -

39 # define FUNC printf_frexpl -

40 # define DOUBLE long double -

41 # define MIN_EXP LDBL_MIN_EXP -

42 # if HAVE_FREXPL_IN_LIBC && HAVE_LDEXPL_IN_LIBC -

43 # define USE_FREXP_LDEXP -

44 # define FREXP frexpl -

45 # define LDEXP ldexpl -

46 # endif -

47 # define DECL_ROUNDING DECL_LONG_DOUBLE_ROUNDING -

48 # define BEGIN_ROUNDING() BEGIN_LONG_DOUBLE_ROUNDING () -

49 # define END_ROUNDING() END_LONG_DOUBLE_ROUNDING () -

50 # define L_(literal) literal##L -

51 #else -

52 # define FUNC printf_frexp -

53 # define DOUBLE double -

54 # define MIN_EXP DBL_MIN_EXP -

55 # if HAVE_FREXP_IN_LIBC && HAVE_LDEXP_IN_LIBC -

56 # define USE_FREXP_LDEXP -

57 # define FREXP frexp -

58 # define LDEXP ldexp -

59 # endif -

60 # define DECL_ROUNDING -

61 # define BEGIN_ROUNDING() -

62 # define END_ROUNDING() -

63 # define L_(literal) literal -

64 #endif -

65 -

66 DOUBLE -

67 FUNC (DOUBLE x, int *expptr) -

68 { -

69 int exponent; -

70 DECL_ROUNDING -

71 -

72 BEGIN_ROUNDING (); -

73 -

74 #ifdef USE_FREXP_LDEXP -

75 /* frexp and ldexp are usually faster than the loop below. */ -

76 x = FREXP (x, &exponent); -

77 -

78 x = x + x; -

79 exponent -= 1; -

80 -

if (exponent < MIN_EXP - 1)

exponent < (-1021) - 1	Description
TRUE	never evaluated
FALSE	never evaluated

82 { -

83 x = LDEXP (x, exponent - (MIN_EXP - 1)); -

84 exponent = MIN_EXP - 1; -

}

never executed: end of block

86 #else -

87 { -

88 /* Since the exponent is an 'int', it fits in 64 bits. Therefore the -

89 loops are executed no more than 64 times. */ -

90 DOUBLE pow2[64]; /* pow2[i] = 2^2^i */ -

91 DOUBLE powh[64]; /* powh[i] = 2^-2^i */ -

92 int i; -

93 -

94 exponent = 0; -

95 if (x >= L_(1.0)) -

96 { -

97 /* A nonnegative exponent. */ -

98 { -

99 DOUBLE pow2_i; /* = pow2[i] */ -

100 DOUBLE powh_i; /* = powh[i] */ -

101 -

102 /* Invariants: pow2_i = 2^2^i, powh_i = 2^-2^i, -

103 x * 2^exponent = argument, x >= 1.0. */ -

104 for (i = 0, pow2_i = L_(2.0), powh_i = L_(0.5); -

105 ; -

106 i++, pow2_i = pow2_i * pow2_i, powh_i = powh_i * powh_i) -

107 { -

108 if (x >= pow2_i) -

109 { -

110 exponent += (1 << i); -

111 x *= powh_i; -

112 } -

113 else -

114 break; -

115 -

116 pow2[i] = pow2_i; -

117 powh[i] = powh_i; -

118 } -

119 } -

120 /* Here 1.0 <= x < 2^2^i. */ -

121 } -

122 else -

123 { -

124 /* A negative exponent. */ -

125 { -

126 DOUBLE pow2_i; /* = pow2[i] */ -

127 DOUBLE powh_i; /* = powh[i] */ -

128 -

129 /* Invariants: pow2_i = 2^2^i, powh_i = 2^-2^i, -

130 x * 2^exponent = argument, x < 1.0, exponent >= MIN_EXP - 1. */ -

131 for (i = 0, pow2_i = L_(2.0), powh_i = L_(0.5); -

132 ; -

133 i++, pow2_i = pow2_i * pow2_i, powh_i = powh_i * powh_i) -

134 { -

135 if (exponent - (1 << i) < MIN_EXP - 1) -

136 break; -

137 -

138 exponent -= (1 << i); -

139 x *= pow2_i; -

140 if (x >= L_(1.0)) -

141 break; -

142 -

143 pow2[i] = pow2_i; -

144 powh[i] = powh_i; -

145 } -

146 } -

147 /* Here either x < 1.0 and exponent - 2^i < MIN_EXP - 1 <= exponent, -

148 or 1.0 <= x < 2^2^i and exponent >= MIN_EXP - 1. */ -

149 -

150 if (x < L_(1.0)) -

151 /* Invariants: x * 2^exponent = argument, x < 1.0 and -

152 exponent - 2^i < MIN_EXP - 1 <= exponent. */ -

153 while (i > 0) -

154 { -

155 i--; -

156 if (exponent - (1 << i) >= MIN_EXP - 1) -

157 { -

158 exponent -= (1 << i); -

159 x *= pow2[i]; -

160 if (x >= L_(1.0)) -

161 break; -

162 } -

163 } -

164 -

165 /* Here either x < 1.0 and exponent = MIN_EXP - 1, -

166 or 1.0 <= x < 2^2^i and exponent >= MIN_EXP - 1. */ -

167 } -

168 -

169 /* Invariants: x * 2^exponent = argument, and -

170 either x < 1.0 and exponent = MIN_EXP - 1, -

171 or 1.0 <= x < 2^2^i and exponent >= MIN_EXP - 1. */ -

172 while (i > 0) -

173 { -

174 i--; -

175 if (x >= pow2[i]) -

176 { -

177 exponent += (1 << i); -

178 x *= powh[i]; -

179 } -

180 } -

181 /* Here either x < 1.0 and exponent = MIN_EXP - 1, -

182 or 1.0 <= x < 2.0 and exponent >= MIN_EXP - 1. */ -

183 } -

184 #endif -

185 -

186 END_ROUNDING (); -

187 -

188 *expptr = exponent; -

189

return x;

never executed: return x;

190 } -

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