1 /* atof_vax.c - turn a Flonum into a VAX floating point number
2 Copyright 1987, 1992, 1993, 1995, 1997, 1999, 2000, 2005, 2007
3 Free Software Foundation, Inc.
5 This file is part of GAS, the GNU Assembler.
7 GAS is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2, or (at your option)
12 GAS is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with GAS; see the file COPYING. If not, write to the Free
19 Software Foundation, 51 Franklin Street - Fifth Floor, Boston, MA
24 /* Precision in LittleNums. */
25 #define MAX_PRECISION 8
31 /* Length in LittleNums of guard bits. */
34 int flonum_gen2vax (int, FLONUM_TYPE
*, LITTLENUM_TYPE
*);
36 /* Number of chars in flonum type 'letter'. */
39 atof_vax_sizeof (int letter
)
43 /* Permitting uppercase letters is probably a bad idea.
44 Please use only lower-cased letters in case the upper-cased
45 ones become unsupported! */
73 static const long mask
[] =
111 /* Shared between flonum_gen2vax and next_bits. */
112 static int bits_left_in_littlenum
;
113 static LITTLENUM_TYPE
*littlenum_pointer
;
114 static LITTLENUM_TYPE
*littlenum_end
;
117 next_bits (int number_of_bits
)
121 if (littlenum_pointer
< littlenum_end
)
123 if (number_of_bits
>= bits_left_in_littlenum
)
125 return_value
= mask
[bits_left_in_littlenum
] & *littlenum_pointer
;
126 number_of_bits
-= bits_left_in_littlenum
;
127 return_value
<<= number_of_bits
;
128 bits_left_in_littlenum
= LITTLENUM_NUMBER_OF_BITS
- number_of_bits
;
130 if (littlenum_pointer
>= littlenum_end
)
131 return_value
|= ((*littlenum_pointer
) >> (bits_left_in_littlenum
)) & mask
[number_of_bits
];
135 bits_left_in_littlenum
-= number_of_bits
;
136 return_value
= mask
[number_of_bits
] & ((*littlenum_pointer
) >> bits_left_in_littlenum
);
142 make_invalid_floating_point_number (LITTLENUM_TYPE
*words
)
144 *words
= 0x8000; /* Floating Reserved Operand Code. */
148 static int /* 0 means letter is OK. */
149 what_kind_of_float (int letter
, /* In: lowercase please. What kind of float? */
150 int *precisionP
, /* Number of 16-bit words in the float. */
151 long *exponent_bitsP
) /* Number of exponent bits. */
159 *precisionP
= F_PRECISION
;
164 *precisionP
= D_PRECISION
;
169 *precisionP
= G_PRECISION
;
170 *exponent_bitsP
= 11;
174 *precisionP
= H_PRECISION
;
175 *exponent_bitsP
= 15;
185 /* Warning: this returns 16-bit LITTLENUMs, because that is
186 what the VAX thinks in. It is up to the caller to figure
187 out any alignment problems and to conspire for the bytes/word
188 to be emitted in the right order. Bigendians beware! */
191 atof_vax (char *str
, /* Text to convert to binary. */
192 int what_kind
, /* 'd', 'f', 'g', 'h' */
193 LITTLENUM_TYPE
*words
) /* Build the binary here. */
196 LITTLENUM_TYPE bits
[MAX_PRECISION
+ MAX_PRECISION
+ GUARD
];
197 /* Extra bits for zeroed low-order bits.
198 The 1st MAX_PRECISION are zeroed,
199 the last contain flonum bits. */
201 int precision
; /* Number of 16-bit words in the format. */
205 f
.low
= bits
+ MAX_PRECISION
;
211 if (what_kind_of_float (what_kind
, &precision
, &exponent_bits
))
214 make_invalid_floating_point_number (words
);
219 memset (bits
, '\0', sizeof (LITTLENUM_TYPE
) * MAX_PRECISION
);
221 /* Use more LittleNums than seems
222 necessary: the highest flonum may have
223 15 leading 0 bits, so could be useless. */
224 f
.high
= f
.low
+ precision
- 1 + GUARD
;
226 if (atof_generic (&return_value
, ".", "eE", &f
))
228 make_invalid_floating_point_number (words
);
231 else if (flonum_gen2vax (what_kind
, &f
, words
))
238 /* In: a flonum, a vax floating point format.
239 Out: a vax floating-point bit pattern. */
242 flonum_gen2vax (int format_letter
, /* One of 'd' 'f' 'g' 'h'. */
244 LITTLENUM_TYPE
*words
) /* Deliver answer here. */
249 int return_value
; /* 0 == OK. */
251 return_value
= what_kind_of_float (format_letter
, &precision
, &exponent_bits
);
253 if (return_value
!= 0)
254 make_invalid_floating_point_number (words
);
258 if (f
->low
> f
->leader
)
260 memset (words
, '\0', sizeof (LITTLENUM_TYPE
) * precision
);
268 int exponent_skippage
;
269 LITTLENUM_TYPE word1
;
271 /* JF: Deal with new Nan, +Inf and -Inf codes. */
272 if (f
->sign
!= '-' && f
->sign
!= '+')
274 make_invalid_floating_point_number (words
);
278 /* All vaxen floating_point formats (so far) have:
280 Bits 14:n are excess-whatever exponent.
281 Bits n-1:0 (if any) are most significant bits of fraction.
282 Bits 15:0 of the next word are the next most significant bits.
283 And so on for each other word.
285 All this to be compatible with a KF11?? (Which is still faster
286 than lots of vaxen I can think of, but it also has higher
287 maintenance costs ... sigh).
289 So we need: number of bits of exponent, number of bits of
292 bits_left_in_littlenum
= LITTLENUM_NUMBER_OF_BITS
;
293 littlenum_pointer
= f
->leader
;
294 littlenum_end
= f
->low
;
295 /* Seek (and forget) 1st significant bit. */
296 for (exponent_skippage
= 0;
298 exponent_skippage
++);;
300 exponent_1
= f
->exponent
+ f
->leader
+ 1 - f
->low
;
301 /* Radix LITTLENUM_RADIX, point just higher than f->leader. */
302 exponent_2
= exponent_1
* LITTLENUM_NUMBER_OF_BITS
;
304 exponent_3
= exponent_2
- exponent_skippage
;
305 /* Forget leading zeros, forget 1st bit. */
306 exponent_4
= exponent_3
+ (1 << (exponent_bits
- 1));
307 /* Offset exponent. */
309 if (exponent_4
& ~mask
[exponent_bits
])
311 /* Exponent overflow. Lose immediately. */
312 make_invalid_floating_point_number (words
);
314 /* We leave return_value alone: admit we read the
315 number, but return a floating exception
316 because we can't encode the number. */
322 /* Word 1. Sign, exponent and perhaps high bits.
323 Assume 2's complement integers. */
324 word1
= (((exponent_4
& mask
[exponent_bits
]) << (15 - exponent_bits
))
325 | ((f
->sign
== '+') ? 0 : 0x8000)
326 | next_bits (15 - exponent_bits
));
329 /* The rest of the words are just mantissa bits. */
330 for (; lp
< words
+ precision
; lp
++)
331 *lp
= next_bits (LITTLENUM_NUMBER_OF_BITS
);
335 /* Since the NEXT bit is a 1, round UP the mantissa.
336 The cunning design of these hidden-1 floats permits
337 us to let the mantissa overflow into the exponent, and
338 it 'does the right thing'. However, we lose if the
339 highest-order bit of the lowest-order word flips.
344 #if (sizeof(carry)) < ((sizeof(bits[0]) * BITS_PER_CHAR) + 2)
345 Please allow at least 1 more bit in carry than is in a LITTLENUM.
346 We need that extra bit to hold a carry during a LITTLENUM carry
347 propagation. Another extra bit (kept 0) will assure us that we
348 don't get a sticky sign bit after shifting right, and that
349 permits us to propagate the carry without any masking of bits.
351 for (carry
= 1, lp
--;
352 carry
&& (lp
>= words
);
357 carry
>>= LITTLENUM_NUMBER_OF_BITS
;
360 if ((word1
^ *words
) & (1 << (LITTLENUM_NUMBER_OF_BITS
- 1)))
362 make_invalid_floating_point_number (words
);
363 /* We leave return_value alone: admit we read the
364 number, but return a floating exception
365 because we can't encode the number. */
374 /* JF this used to be in vax.c but this looks like a better place for it. */
376 /* In: input_line_pointer->the 1st character of a floating-point
378 1 letter denoting the type of statement that wants a
379 binary floating point number returned.
380 Address of where to build floating point literal.
381 Assumed to be 'big enough'.
382 Address of where to return size of literal (in chars).
384 Out: Input_line_pointer->of next char after floating number.
386 Floating point literal.
387 Number of chars we used for the literal. */
389 #define MAXIMUM_NUMBER_OF_LITTLENUMS 8 /* For .hfloats. */
392 md_atof (int what_statement_type
,
396 LITTLENUM_TYPE words
[MAXIMUM_NUMBER_OF_LITTLENUMS
];
398 unsigned int number_of_chars
;
399 LITTLENUM_TYPE
*littlenumP
;
401 switch (what_statement_type
)
428 LITTLENUM_TYPE
*limit
;
430 input_line_pointer
= atof_vax (input_line_pointer
,
433 /* The atof_vax() builds up 16-bit numbers.
434 Since the assembler may not be running on
435 a little-endian machine, be very careful about
436 converting words to chars. */
437 number_of_chars
= atof_vax_sizeof (kind_of_float
);
438 know (number_of_chars
<= MAXIMUM_NUMBER_OF_LITTLENUMS
* sizeof (LITTLENUM_TYPE
));
439 limit
= words
+ (number_of_chars
/ sizeof (LITTLENUM_TYPE
));
440 for (littlenumP
= words
; littlenumP
< limit
; littlenumP
++)
442 md_number_to_chars (literalP
, *littlenumP
, sizeof (LITTLENUM_TYPE
));
443 literalP
+= sizeof (LITTLENUM_TYPE
);
449 *sizeP
= number_of_chars
;
450 return kind_of_float
? NULL
: _("Bad call to md_atof()");