4 * Floating point read/write functions.
6 * Copyright 2010 - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
8 * Permission is hereby granted, free of charge, to any person obtaining a copy
9 * of this software and associated documentation files (the "Software"), to deal
10 * in the Software without restriction, including without limitation the rights
11 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
12 * copies of the Software, and to permit persons to whom the Software is
13 * furnished to do so, subject to the following conditions:
15 * The above copyright notice and this permission notice shall be included in
16 * all copies or substantial portions of the Software.
18 * Reference: ISO C99 standard 5.2.4
21 #include <babeltrace/ctf/types.h>
23 #include <float.h> /* C99 floating point definitions */
24 #include <limits.h> /* C99 limits */
28 * This library is limited to binary representation of floating point values.
29 * Sign-extension of the exponents is assumed to keep the NaN, +inf, -inf
30 * values, but this should be double-checked (TODO).
34 * Aliasing float/double and unsigned long is not strictly permitted by strict
35 * aliasing, but in practice declaration prunning is well supported, and this permits
36 * us to use per-word read/writes rather than per-byte.
39 #if defined(__GNUC__) || defined(__MINGW32__) || defined(_MSC_VER)
40 #define HAS_TYPE_PRUNING
45 #error "Unsupported floating point radix"
51 #ifdef HAS_TYPE_PRUNING
52 unsigned long bits
[(sizeof(double) + sizeof(unsigned long) - 1) / sizeof(unsigned long)];
54 unsigned char bits
[sizeof(double)];
58 union ldoubleIEEE754
{
60 #ifdef HAS_TYPE_PRUNING
61 unsigned long bits
[(sizeof(long double) + sizeof(unsigned long) - 1) / sizeof(unsigned long)];
63 unsigned char bits
[sizeof(long double)];
67 static struct declaration_float
*static_ldouble_declaration
;
70 size_t sign_start
, exp_start
, mantissa_start
, len
;
73 void _ctf_float_copy(struct stream_pos
*destp
,
74 struct definition_float
*dest_definition
,
75 struct stream_pos
*srcp
,
76 const struct definition_float
*src_definition
)
79 if (src_definition
->declaration
->byte_order
== LITTLE_ENDIAN
) {
80 ctf_integer_read(srcp
, &src_definition
->mantissa
->p
);
81 ctf_integer_read(srcp
, &src_definition
->exp
->p
);
82 ctf_integer_read(srcp
, &src_definition
->sign
->p
);
84 ctf_integer_read(srcp
, &src_definition
->sign
->p
);
85 ctf_integer_read(srcp
, &src_definition
->exp
->p
);
86 ctf_integer_read(srcp
, &src_definition
->mantissa
->p
);
89 dest_definition
->mantissa
->value
._unsigned
=
90 src_definition
->mantissa
->value
._unsigned
;
91 dest_definition
->exp
->value
._signed
=
92 src_definition
->exp
->value
._signed
;
93 dest_definition
->sign
->value
._unsigned
=
94 src_definition
->sign
->value
._unsigned
;
97 if (dest_definition
->declaration
->byte_order
== LITTLE_ENDIAN
) {
98 ctf_integer_write(destp
, &dest_definition
->mantissa
->p
);
99 ctf_integer_write(destp
, &dest_definition
->exp
->p
);
100 ctf_integer_write(destp
, &dest_definition
->sign
->p
);
102 ctf_integer_write(destp
, &dest_definition
->sign
->p
);
103 ctf_integer_write(destp
, &dest_definition
->exp
->p
);
104 ctf_integer_write(destp
, &dest_definition
->mantissa
->p
);
108 void ctf_float_read(struct stream_pos
*ppos
, struct definition
*definition
)
110 struct definition_float
*float_definition
=
111 container_of(definition
, struct definition_float
, p
);
112 const struct declaration_float
*float_declaration
=
113 float_definition
->declaration
;
114 struct ctf_stream_pos
*pos
= ctf_pos(ppos
);
115 union ldoubleIEEE754 u
;
116 struct definition
*tmpdef
=
117 static_ldouble_declaration
->p
.definition_new(&static_ldouble_declaration
->p
,
119 struct definition_float
*tmpfloat
=
120 container_of(tmpdef
, struct definition_float
, p
);
121 struct ctf_stream_pos destp
;
123 ctf_init_pos(&destp
, -1, O_WRONLY
);
124 destp
.base
= (char *) u
.bits
;
126 ctf_align_pos(pos
, float_declaration
->p
.alignment
);
127 _ctf_float_copy(&destp
.parent
, tmpfloat
, ppos
, float_definition
);
128 float_definition
->value
= u
.v
;
129 definition_unref(tmpdef
);
132 void ctf_float_write(struct stream_pos
*ppos
, struct definition
*definition
)
134 struct definition_float
*float_definition
=
135 container_of(definition
, struct definition_float
, p
);
136 const struct declaration_float
*float_declaration
=
137 float_definition
->declaration
;
138 struct ctf_stream_pos
*pos
= ctf_pos(ppos
);
139 union ldoubleIEEE754 u
;
140 struct definition
*tmpdef
=
141 static_ldouble_declaration
->p
.definition_new(&static_ldouble_declaration
->p
,
143 struct definition_float
*tmpfloat
=
144 container_of(tmpdef
, struct definition_float
, p
);
145 struct ctf_stream_pos srcp
;
147 ctf_init_pos(&srcp
, -1, O_RDONLY
);
148 srcp
.base
= (char *) u
.bits
;
150 u
.v
= float_definition
->value
;
151 ctf_align_pos(pos
, float_declaration
->p
.alignment
);
152 _ctf_float_copy(ppos
, float_definition
, &srcp
.parent
, tmpfloat
);
153 definition_unref(tmpdef
);
156 void __attribute__((constructor
)) ctf_float_init(void)
158 static_ldouble_declaration
=
159 float_declaration_new(LDBL_MANT_DIG
,
160 sizeof(long double) * CHAR_BIT
- LDBL_MANT_DIG
,
162 __alignof__(long double));
165 void __attribute__((destructor
)) ctf_float_fini(void)
167 declaration_unref(&static_ldouble_declaration
->p
);