2 * Copyright (C) 1995-2011 University of Karlsruhe. All right reserved.
4 * This file is part of libFirm.
6 * This file may be distributed and/or modified under the terms of the
7 * GNU General Public License version 2 as published by the Free Software
8 * Foundation and appearing in the file LICENSE.GPL included in the
9 * packaging of this file.
11 * Licensees holding valid libFirm Professional Edition licenses may use
12 * this file in accordance with the libFirm Commercial License.
13 * Agreement provided with the Software.
15 * This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
16 * WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * @brief tarval floating point calculations
24 * @author Mathias Heil
27 #ifndef FIRM_TV_FLTCALC_H
28 #define FIRM_TV_FLTCALC_H
31 #include "firm_types.h"
40 /** IEEE-754 Rounding modes. */
42 FC_TONEAREST, /**< if unsure, to the nearest even */
43 FC_TOPOSITIVE, /**< to +oo */
44 FC_TONEGATIVE, /**< to -oo */
45 FC_TOZERO /**< to 0 */
48 #define FC_DEFAULT_PRECISION 64
51 * possible float states
54 FC_NORMAL, /**< normal representation, implicit 1 */
56 FC_SUBNORMAL, /**< denormals, implicit 0 */
58 FC_NAN, /**< Not A Number */
62 * A descriptor for an IEEE float value.
64 typedef struct ieee_descriptor_t {
65 unsigned char exponent_size; /**< size of exponent in bits */
66 unsigned char mantissa_size; /**< size of mantissa in bits */
67 unsigned char explicit_one; /**< set if the leading one is explicit */
71 typedef struct fp_value fp_value;
74 /** internal buffer access
75 * All functions that accept NULL as return buffer put their result into an
77 * @return fc_get_buffer() returns the pointer to the buffer, fc_get_buffer_length()
78 * returns the size of this buffer
80 const void *fc_get_buffer(void);
81 int fc_get_buffer_length(void);
84 void *fc_val_from_str(const char *str, size_t len, const ieee_descriptor_t *desc, void *result);
86 /** get the representation of a floating point value
87 * This function tries to builds a representation having the same value as the
88 * float number passed.
89 * If the wished precision is less than the precision of long double the value
90 * built will be rounded. Therefore only an approximation of the passed float
91 * can be expected in this case.
93 * @param l The floating point number to build a representation for
94 * @param desc The floating point descriptor
95 * @param result A buffer to hold the value built. If this is NULL, the internal
96 * accumulator buffer is used. Note that the buffer must be big
97 * enough to hold the value. Use fc_get_buffer_length() to find out
100 * @return The result pointer passed to the function. If this was NULL this returns
101 * a pointer to the internal accumulator buffer
103 fp_value *fc_val_from_ieee754(long double l, const ieee_descriptor_t *desc,
106 /** retrieve the float value of an internal value
107 * This function casts the internal value to long double and returns a
108 * long double with that value.
109 * This implies that values of higher precision than long double are subject to
110 * rounding, so the returned value might not the same than the actually
113 * @param val The representation of a float value
115 * @return a float value approximating the represented value
117 long double fc_val_to_ieee754(const fp_value *val);
119 /** cast a value to another precision
120 * This function changes the precision of a float representation.
121 * If the new precision is less than the original precision the returned
122 * value might not be the same as the original value.
124 * @param val The value to be casted
125 * @param desc The floating point descriptor
126 * @param result A buffer to hold the value built. If this is NULL, the internal
127 * accumulator buffer is used. Note that the buffer must be big
128 * enough to hold the value. Use fc_get_buffer_length() to find out
130 * @return The result pointer passed to the function. If this was NULL this returns
131 * a pointer to the internal accumulator buffer
133 fp_value *fc_cast(const fp_value *val, const ieee_descriptor_t *desc, fp_value *result);
136 /** build a special float value
137 * This function builds a representation for a special float value, as indicated by the
140 * @param desc The floating point descriptor
141 * @param result A buffer to hold the value built. If this is NULL, the internal
142 * accumulator buffer is used. Note that the buffer must be big
143 * enough to hold the value. Use fc_get_buffer_length() to find out
145 * @return The result pointer passed to the function. If this was NULL this returns
146 * a pointer to the internal accumulator buffer
148 fp_value *fc_get_min(const ieee_descriptor_t *desc, fp_value *result);
149 fp_value *fc_get_max(const ieee_descriptor_t *desc, fp_value *result);
150 fp_value *fc_get_snan(const ieee_descriptor_t *desc, fp_value *result);
151 fp_value *fc_get_qnan(const ieee_descriptor_t *desc, fp_value *result);
152 fp_value *fc_get_plusinf(const ieee_descriptor_t *desc, fp_value *result);
153 fp_value *fc_get_minusinf(const ieee_descriptor_t *desc, fp_value *result);
156 int fc_is_zero(const fp_value *a);
157 int fc_is_negative(const fp_value *a);
158 int fc_is_inf(const fp_value *a);
159 int fc_is_nan(const fp_value *a);
160 int fc_is_subnormal(const fp_value *a);
162 fp_value *fc_add(const fp_value *a, const fp_value *b, fp_value *result);
163 fp_value *fc_sub(const fp_value *a, const fp_value *b, fp_value *result);
164 fp_value *fc_mul(const fp_value *a, const fp_value *b, fp_value *result);
165 fp_value *fc_div(const fp_value *a, const fp_value *b, fp_value *result);
166 fp_value *fc_neg(const fp_value *a, fp_value *result);
167 fp_value *fc_int(const fp_value *a, fp_value *result);
168 fp_value *fc_rnd(const fp_value *a, fp_value *result);
170 char *fc_print(const fp_value *a, char *buf, int buflen, unsigned base);
172 /** Compare two values
173 * This function compares two values
175 * @param a Value No. 1
176 * @param b Value No. 2
177 * @result The returned value will be one of
181 * 2 if either value is NaN
183 int fc_comp(const fp_value *a, const fp_value *b);
186 * Converts an floating point value into an integer value.
188 int fc_flt2int(const fp_value *a, void *result, ir_mode *dst_mode);
191 * Returns non-zero if the mantissa is zero, i.e. 1.0Exxx
193 int fc_zero_mantissa(const fp_value *value);
196 * Returns the exponent of a value.
198 int fc_get_exponent(const fp_value *value);
201 * Return non-zero if a given value can be converted lossless into another precision.
203 int fc_can_lossless_conv_to(const fp_value *value, const ieee_descriptor_t *desc);
205 /** Set new rounding mode
206 * This function sets the rounding mode to one of the following, returning
207 * the previously set rounding mode.
208 * FC_TONEAREST (default):
209 * Any unrepresentable value is rounded to the nearest representable
210 * value. If it lies in the middle the value with the least significant
211 * bit of zero is chosen (the even one).
212 * Values too big to represent will round to +/-infinity.
214 * Any unrepresentable value is rounded towards negative infinity.
215 * Positive values too big to represent will round to the biggest
216 * representable value, negative values too small to represent will
217 * round to -infinity.
219 * Any unrepresentable value is rounded towards positive infinity
220 * Negative values too small to represent will round to the biggest
221 * representable value, positive values too big to represent will
222 * round to +infinity.
224 * Any unrepresentable value is rounded towards zero, effectively
225 * chopping off any bits beyond the mantissa size.
226 * Values too big to represent will round to the biggest/smallest
227 * representable value.
229 * These modes correspond to the modes required by the IEEE-754 standard.
231 * @param mode The new rounding mode. Any value other than the four
232 * defined values will have no effect.
233 * @return The previous rounding mode.
235 * @see fc_get_rounding_mode()
236 * @see IEEE754, IEEE854 Floating Point Standard
238 fc_rounding_mode_t fc_set_rounding_mode(fc_rounding_mode_t mode);
240 /** Get the rounding mode
241 * This function retrieves the currently used rounding mode
243 * @return The current rounding mode
244 * @see fc_set_rounding_mode()
246 fc_rounding_mode_t fc_get_rounding_mode(void);
248 /** Get bit representation of a value
249 * This function allows to read a value in encoded form, byte wise.
250 * The value will be packed corresponding to the way used by the IEEE
251 * encoding formats, i.e.
253 * exp_size bits exponent + bias
254 * mant_size bits mantissa, without leading 1
256 * As in IEEE, an exponent of 0 indicates a denormalized number, which
257 * implies a most significant bit of zero instead of one; an exponent
258 * of all ones (2**exp_size - 1) encodes infinity if the mantissa is
259 * all zeros, else Not A Number.
261 * @param val A pointer to the value. If NULL is passed a copy of the
262 * most recent value passed to this function is used, saving the
263 * packing step. This behavior may be changed in the future.
264 * @param num_bit The maximum number of bits to return. Any bit beyond
265 * num_bit will be returned as zero.
266 * @param byte_ofs The byte index to read, 0 is the least significant
268 * @return 8 bits of encoded data
270 unsigned char fc_sub_bits(const fp_value *val, unsigned num_bit, unsigned byte_ofs);
273 * Set the immediate precision for IEEE-754 results. Set this to
274 * 0 to get the same precision as the operands.
275 * For x87 compatibility, set this to 80.
277 * @return the old setting
279 unsigned fc_set_immediate_precision(unsigned bits);
282 * Returns non-zero if the result of the last operation was exact.
284 int fc_is_exact(void);
286 void init_fltcalc(int precision);
287 void finish_fltcalc(void);
289 #endif /* FIRM_TV_FLTCALC_H */