1 /* atof_ns32k.c - turn a Flonum into a ns32k floating point number
2 Copyright (C) 1987 Free Software Foundation, Inc.
4 This file is part of GAS, the GNU Assembler.
6 GAS is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 1, or (at your option)
11 GAS is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with GAS; see the file COPYING. If not, write to
18 the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
20 /* this is atof-m68k.c hacked for ns32k */
24 extern FLONUM_TYPE generic_floating_point_number; /* Flonums returned here. */
26 extern char EXP_CHARS[];
27 /* Precision in LittleNums. */
28 #define MAX_PRECISION (4)
29 #define F_PRECISION (2)
30 #define D_PRECISION (4)
32 /* Length in LittleNums of guard bits. */
35 int /* Number of chars in flonum type 'letter'. */
42 * Permitting uppercase letters is probably a bad idea.
43 * Please use only lower-cased letters in case the upper-cased
44 * ones become unsupported!
49 return_value = F_PRECISION;
53 return_value = D_PRECISION;
60 return (return_value);
63 static unsigned long int mask[] = {
99 static int bits_left_in_littlenum;
100 static int littlenums_left;
101 static LITTLENUM_TYPE * littlenum_pointer;
104 next_bits (number_of_bits)
109 if (!littlenums_left)
111 if (number_of_bits >= bits_left_in_littlenum)
113 return_value = mask[bits_left_in_littlenum] & *littlenum_pointer;
114 number_of_bits -= bits_left_in_littlenum;
115 return_value <<= number_of_bits;
116 if (littlenums_left) {
117 bits_left_in_littlenum = LITTLENUM_NUMBER_OF_BITS - number_of_bits;
118 littlenum_pointer --;
120 return_value |= (*littlenum_pointer>>bits_left_in_littlenum) & mask[number_of_bits];
125 bits_left_in_littlenum -= number_of_bits;
126 return_value = mask[number_of_bits] & (*littlenum_pointer>>bits_left_in_littlenum);
128 return (return_value);
132 make_invalid_floating_point_number (words)
133 LITTLENUM_TYPE * words;
135 /* Zero the leftmost bit */
136 words[0]= (LITTLENUM_TYPE) ((unsigned)-1)>>1;
137 words[1]= (LITTLENUM_TYPE) -1;
138 words[2]= (LITTLENUM_TYPE) -1;
139 words[3]= (LITTLENUM_TYPE) -1;
142 /***********************************************************************\
144 * Warning: this returns 16-bit LITTLENUMs, because that is *
145 * what the VAX thinks in. It is up to the caller to figure *
146 * out any alignment problems and to conspire for the bytes/word *
147 * to be emitted in the right order. Bigendians beware! *
149 \***********************************************************************/
151 char * /* Return pointer past text consumed. */
152 atof_ns32k (str, what_kind, words)
153 char * str; /* Text to convert to binary. */
154 char what_kind; /* 'd', 'f', 'g', 'h' */
155 LITTLENUM_TYPE * words; /* Build the binary here. */
158 LITTLENUM_TYPE bits[MAX_PRECISION + MAX_PRECISION + GUARD];
159 /* Extra bits for zeroed low-order bits. */
160 /* The 1st MAX_PRECISION are zeroed, */
161 /* the last contain flonum bits. */
163 int precision; /* Number of 16-bit words in the format. */
164 long int exponent_bits;
170 int exponent_skippage;
171 LITTLENUM_TYPE word1;
175 f.low = bits + MAX_PRECISION;
181 /* Use more LittleNums than seems */
182 /* necessary: the highest flonum may have */
183 /* 15 leading 0 bits, so could be useless. */
185 bzero (bits, sizeof(LITTLENUM_TYPE) * MAX_PRECISION);
189 precision = F_PRECISION;
194 precision = D_PRECISION;
199 make_invalid_floating_point_number (words);
203 f.high = f.low + precision - 1 + GUARD;
205 if (atof_generic (& return_value, ".", EXP_CHARS, & f)) {
206 as_warn("Error converting floating point number (Exponent overflow?)");
207 make_invalid_floating_point_number (words);
211 if (f.low > f.leader) {
213 bzero (words, sizeof(LITTLENUM_TYPE) * precision);
217 if (f.sign != '+' && f.sign != '-') {
218 make_invalid_floating_point_number(words);
224 * All vaxen floating_point formats (so far) have:
225 * Bit 15 is sign bit.
226 * Bits 14:n are excess-whatever exponent.
227 * Bits n-1:0 (if any) are most significant bits of fraction.
228 * Bits 15:0 of the next word are the next most significant bits.
229 * And so on for each other word.
231 * So we need: number of bits of exponent, number of bits of
234 bits_left_in_littlenum = LITTLENUM_NUMBER_OF_BITS;
235 littlenum_pointer = f.leader;
236 littlenums_left = 1 + f.leader-f.low;
237 /* Seek (and forget) 1st significant bit */
238 for (exponent_skippage = 0;! next_bits(1); exponent_skippage ++)
240 exponent_1 = f.exponent + f.leader + 1 - f.low;
241 /* Radix LITTLENUM_RADIX, point just higher than f.leader. */
242 exponent_2 = exponent_1 * LITTLENUM_NUMBER_OF_BITS;
244 exponent_3 = exponent_2 - exponent_skippage;
245 /* Forget leading zeros, forget 1st bit. */
246 exponent_4 = exponent_3 + ((1 << (exponent_bits - 1)) - 2);
247 /* Offset exponent. */
249 if (exponent_4 & ~ mask[exponent_bits]) {
251 * Exponent overflow. Lose immediately.
255 * We leave return_value alone: admit we read the
256 * number, but return a floating exception
257 * because we can't encode the number.
260 as_warn("Exponent overflow in floating-point number");
261 make_invalid_floating_point_number (words);
266 /* Word 1. Sign, exponent and perhaps high bits. */
267 /* Assume 2's complement integers. */
268 word1 = ((exponent_4 & mask[exponent_bits]) << (15 - exponent_bits)) |
269 ((f.sign == '+') ? 0 : 0x8000) | next_bits (15 - exponent_bits);
272 /* The rest of the words are just mantissa bits. */
273 for (; lp < words + precision; lp++)
274 * lp = next_bits (LITTLENUM_NUMBER_OF_BITS);
277 unsigned long int carry;
279 * Since the NEXT bit is a 1, round UP the mantissa.
280 * The cunning design of these hidden-1 floats permits
281 * us to let the mantissa overflow into the exponent, and
282 * it 'does the right thing'. However, we lose if the
283 * highest-order bit of the lowest-order word flips.
288 /* #if (sizeof(carry)) < ((sizeof(bits[0]) * BITS_PER_CHAR) + 2)
289 Please allow at least 1 more bit in carry than is in a LITTLENUM.
290 We need that extra bit to hold a carry during a LITTLENUM carry
291 propagation. Another extra bit (kept 0) will assure us that we
292 don't get a sticky sign bit after shifting right, and that
293 permits us to propagate the carry without any masking of bits.
295 for (carry = 1, lp --; carry && (lp >= words); lp --) {
296 carry = * lp + carry;
298 carry >>= LITTLENUM_NUMBER_OF_BITS;
300 if ( (word1 ^ *words) & (1 << (LITTLENUM_NUMBER_OF_BITS - 1)) ) {
301 /* We leave return_value alone: admit we read the
302 * number, but return a floating exception
303 * because we can't encode the number.
305 make_invalid_floating_point_number (words);
309 return (return_value);
312 /* This is really identical to atof_ns32k except for some details */
314 gen_to_words(words,precision,exponent_bits)
315 LITTLENUM_TYPE *words;
316 long int exponent_bits;
324 int exponent_skippage;
325 LITTLENUM_TYPE word1;
328 if (generic_floating_point_number.low > generic_floating_point_number.leader) {
330 bzero (words, sizeof(LITTLENUM_TYPE) * precision);
335 * All vaxen floating_point formats (so far) have:
336 * Bit 15 is sign bit.
337 * Bits 14:n are excess-whatever exponent.
338 * Bits n-1:0 (if any) are most significant bits of fraction.
339 * Bits 15:0 of the next word are the next most significant bits.
340 * And so on for each other word.
342 * So we need: number of bits of exponent, number of bits of
345 bits_left_in_littlenum = LITTLENUM_NUMBER_OF_BITS;
346 littlenum_pointer = generic_floating_point_number.leader;
347 littlenums_left = 1+generic_floating_point_number.leader - generic_floating_point_number.low;
348 /* Seek (and forget) 1st significant bit */
349 for (exponent_skippage = 0;! next_bits(1); exponent_skippage ++)
351 exponent_1 = generic_floating_point_number.exponent + generic_floating_point_number.leader + 1 -
352 generic_floating_point_number.low;
353 /* Radix LITTLENUM_RADIX, point just higher than generic_floating_point_number.leader. */
354 exponent_2 = exponent_1 * LITTLENUM_NUMBER_OF_BITS;
356 exponent_3 = exponent_2 - exponent_skippage;
357 /* Forget leading zeros, forget 1st bit. */
358 exponent_4 = exponent_3 + ((1 << (exponent_bits - 1)) - 2);
359 /* Offset exponent. */
361 if (exponent_4 & ~ mask[exponent_bits]) {
363 * Exponent overflow. Lose immediately.
367 * We leave return_value alone: admit we read the
368 * number, but return a floating exception
369 * because we can't encode the number.
372 make_invalid_floating_point_number (words);
377 /* Word 1. Sign, exponent and perhaps high bits. */
378 /* Assume 2's complement integers. */
379 word1 = ((exponent_4 & mask[exponent_bits]) << (15 - exponent_bits)) |
380 ((generic_floating_point_number.sign == '+') ? 0 : 0x8000) | next_bits (15 - exponent_bits);
383 /* The rest of the words are just mantissa bits. */
384 for (; lp < words + precision; lp++)
385 * lp = next_bits (LITTLENUM_NUMBER_OF_BITS);
388 unsigned long int carry;
390 * Since the NEXT bit is a 1, round UP the mantissa.
391 * The cunning design of these hidden-1 floats permits
392 * us to let the mantissa overflow into the exponent, and
393 * it 'does the right thing'. However, we lose if the
394 * highest-order bit of the lowest-order word flips.
399 /* #if (sizeof(carry)) < ((sizeof(bits[0]) * BITS_PER_CHAR) + 2)
400 Please allow at least 1 more bit in carry than is in a LITTLENUM.
401 We need that extra bit to hold a carry during a LITTLENUM carry
402 propagation. Another extra bit (kept 0) will assure us that we
403 don't get a sticky sign bit after shifting right, and that
404 permits us to propagate the carry without any masking of bits.
406 for (carry = 1, lp --; carry && (lp >= words); lp --) {
407 carry = * lp + carry;
409 carry >>= LITTLENUM_NUMBER_OF_BITS;
411 if ( (word1 ^ *words) & (1 << (LITTLENUM_NUMBER_OF_BITS - 1)) ) {
412 /* We leave return_value alone: admit we read the
413 * number, but return a floating exception
414 * because we can't encode the number.
416 make_invalid_floating_point_number (words);
420 return (return_value);
423 /* This routine is a real kludge. Someone really should do it better, but
424 I'm too lazy, and I don't understand this stuff all too well anyway
433 sprintf(buf,"%ld",x);
435 if (atof_generic(&bufp,".", EXP_CHARS, &generic_floating_point_number))
436 as_warn("Error converting number to floating point (Exponent overflow?)");