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1.1 root 1: /* atof_m68k.c - */
2:
3: /* Copyright (C) 1987 Free Software Foundation, Inc.
4:
5: This file is part of Gas, the GNU Assembler.
6:
7: The GNU assembler is distributed in the hope that it will be
8: useful, but WITHOUT ANY WARRANTY. No author or distributor
9: accepts responsibility to anyone for the consequences of using it
10: or for whether it serves any particular purpose or works at all,
11: unless he says so in writing. Refer to the GNU Assembler General
12: Public License for full details.
13:
14: Everyone is granted permission to copy, modify and redistribute
15: the GNU Assembler, but only under the conditions described in the
16: GNU Assembler General Public License. A copy of this license is
17: supposed to have been given to you along with the GNU Assembler
18: so you can know your rights and responsibilities. It should be
19: in a file named COPYING. Among other things, the copyright
20: notice and this notice must be preserved on all copies. */
21:
22: #include "flonum.h"
23:
24: extern FLONUM_TYPE generic_floating_point_number; /* Flonums returned here. */
25: #define NULL (0)
26:
27: extern char EXP_CHARS[];
28: /* Precision in LittleNums. */
29: #define MAX_PRECISION (6)
30: #define F_PRECISION (2)
31: #define D_PRECISION (4)
32: #define X_PRECISION (6)
33: #define P_PRECISION (6)
34:
35: /* Length in LittleNums of guard bits. */
36: #define GUARD (2)
37:
38: int /* Number of chars in flonum type 'letter'. */
39: atof_sizeof (letter)
40: char letter;
41: {
42: int return_value;
43:
44: /*
45: * Permitting uppercase letters is probably a bad idea.
46: * Please use only lower-cased letters in case the upper-cased
47: * ones become unsupported!
48: */
49: switch (letter)
50: {
51: case 'f':
52: case 'F':
53: case 's':
54: case 'S':
55: return_value = F_PRECISION;
56: break;
57:
58: case 'd':
59: case 'D':
60: case 'r':
61: case 'R':
62: return_value = D_PRECISION;
63: break;
64:
65: case 'x':
66: case 'X':
67: return_value = X_PRECISION;
68: break;
69:
70: case 'p':
71: case 'P':
72: return_value = P_PRECISION;
73: break;
74:
75: default:
76: return_value = 0;
77: break;
78: }
79: return (return_value);
80: }
81:
82: static unsigned long int mask [] = {
83: 0x00000000,
84: 0x00000001,
85: 0x00000003,
86: 0x00000007,
87: 0x0000000f,
88: 0x0000001f,
89: 0x0000003f,
90: 0x0000007f,
91: 0x000000ff,
92: 0x000001ff,
93: 0x000003ff,
94: 0x000007ff,
95: 0x00000fff,
96: 0x00001fff,
97: 0x00003fff,
98: 0x00007fff,
99: 0x0000ffff,
100: 0x0001ffff,
101: 0x0003ffff,
102: 0x0007ffff,
103: 0x000fffff,
104: 0x001fffff,
105: 0x003fffff,
106: 0x007fffff,
107: 0x00ffffff,
108: 0x01ffffff,
109: 0x03ffffff,
110: 0x07ffffff,
111: 0x0fffffff,
112: 0x1fffffff,
113: 0x3fffffff,
114: 0x7fffffff,
115: 0xffffffff
116: };
117:
118: static int
119: next_bits (number_of_bits, address_of_bits_left_in_littlenum, address_of_littlenum_pointer)
120: int number_of_bits;
121: int * address_of_bits_left_in_littlenum;
122: LITTLENUM_TYPE ** address_of_littlenum_pointer;
123: {
124: int return_value;
125:
126: if (number_of_bits >= (* address_of_bits_left_in_littlenum))
127: {
128: return_value = mask [(* address_of_bits_left_in_littlenum)] & * (* address_of_littlenum_pointer);
129: number_of_bits -= (* address_of_bits_left_in_littlenum);
130: return_value <<= number_of_bits;
131: (* address_of_bits_left_in_littlenum) = LITTLENUM_NUMBER_OF_BITS - number_of_bits;
132: (* address_of_littlenum_pointer) --; /* JF was --, how could it
133: possibly work! */
134: return_value |= ( (* (* address_of_littlenum_pointer)) >>
135: ((* address_of_bits_left_in_littlenum)) ) & mask [number_of_bits];
136: }
137: else
138: {
139: (* address_of_bits_left_in_littlenum) -= number_of_bits;
140: return_value = mask [number_of_bits] & ( (* (* address_of_littlenum_pointer)) >> (* address_of_bits_left_in_littlenum));
141: }
142: return (return_value);
143: }
144:
145: static void
146: make_invalid_floating_point_number (words)
147: LITTLENUM_TYPE * words;
148: {
149: words[0]= ((unsigned)-1)>>1; /* Zero the leftmost bit */
150: words[1]= -1;
151: words[2]= -1;
152: words[3]= -1;
153: words[4]= -1;
154: words[5]= -1;
155: }
156:
157: /***********************************************************************\
158: * *
159: * Warning: this returns 16-bit LITTLENUMs, because that is *
160: * what the VAX thinks in. It is up to the caller to figure *
161: * out any alignment problems and to conspire for the bytes/word *
162: * to be emitted in the right order. Bigendians beware! *
163: * *
164: \***********************************************************************/
165:
166: char * /* Return pointer past text consumed. */
167: atof_m68k (str, what_kind, words)
168: char * str; /* Text to convert to binary. */
169: char what_kind; /* 'd', 'f', 'g', 'h' */
170: LITTLENUM_TYPE * words; /* Build the binary here. */
171: {
172: FLONUM_TYPE f;
173: LITTLENUM_TYPE bits [MAX_PRECISION + MAX_PRECISION + GUARD];
174: /* Extra bits for zeroed low-order bits. */
175: /* The 1st MAX_PRECISION are zeroed, */
176: /* the last contain flonum bits. */
177: char * return_value;
178: int precision; /* Number of 16-bit words in the format. */
179: long int exponent_bits;
180:
181: long int exponent_1;
182: long int exponent_2;
183: long int exponent_3;
184: long int exponent_4;
185: int exponent_skippage;
186: LITTLENUM_TYPE word1;
187: int bits_left_in_littlenum;
188: LITTLENUM_TYPE * littlenum_pointer;
189: LITTLENUM_TYPE * lp;
190:
191: return_value = str;
192: f.low = bits + MAX_PRECISION;
193: f.high = NULL;
194: f.leader = NULL;
195: f.exponent = NULL;
196: f.sign = '\0';
197:
198: /* Use more LittleNums than seems */
199: /* necessary: the highest flonum may have */
200: /* 15 leading 0 bits, so could be useless. */
201:
202: bzero (bits, sizeof(LITTLENUM_TYPE) * MAX_PRECISION);
203:
204: switch(what_kind) {
205: case 'f':
206: case 'F':
207: case 's':
208: case 'S':
209: precision = F_PRECISION;
210: exponent_bits = 8;
211: break;
212:
213: case 'd':
214: case 'D':
215: case 'r':
216: case 'R':
217: precision = D_PRECISION;
218: exponent_bits = 11;
219: break;
220:
221: case 'x':
222: case 'X':
223: precision = X_PRECISION;
224: exponent_bits = 15;
225: break;
226:
227: case 'p':
228: case 'P':
229:
230: precision = P_PRECISION;
231: exponent_bits= -1;
232: break;
233:
234: default:
235: make_invalid_floating_point_number (words);
236: return NULL;
237: }
238:
239: f.high = f.low + precision - 1 + GUARD;
240:
241: if (atof_generic (& return_value, ".", EXP_CHARS, & f)) {
242: as_warn("Error converting floating point number (Exponent overflow?)");
243: make_invalid_floating_point_number (words);
244: return NULL;
245: }
246:
247: if (f.low > f.leader) {
248: /* 0.0e0 seen. */
249: bzero (words, sizeof(LITTLENUM_TYPE) * precision);
250: return return_value;
251: }
252:
253: /*
254: * All vaxen floating_point formats (so far) have:
255: * Bit 15 is sign bit.
256: * Bits 14:n are excess-whatever exponent.
257: * Bits n-1:0 (if any) are most significant bits of fraction.
258: * Bits 15:0 of the next word are the next most significant bits.
259: * And so on for each other word.
260: *
261: * So we need: number of bits of exponent, number of bits of
262: * mantissa.
263: */
264: bits_left_in_littlenum = LITTLENUM_NUMBER_OF_BITS;
265: littlenum_pointer = f.leader;
266: /* Seek (and forget) 1st significant bit */
267: for (exponent_skippage = 0;! next_bits(1, &bits_left_in_littlenum,
268: &littlenum_pointer); exponent_skippage ++)
269: ;
270: exponent_1 = f.exponent + f.leader + 1 - f.low;
271: /* Radix LITTLENUM_RADIX, point just higher than f.leader. */
272: exponent_2 = exponent_1 * LITTLENUM_NUMBER_OF_BITS;
273: /* Radix 2. */
274: exponent_3 = exponent_2 - exponent_skippage;
275: /* Forget leading zeros, forget 1st bit. */
276: exponent_4 = exponent_3 + ((1 << (exponent_bits - 1)) - 2);
277: /* Offset exponent. */
278:
279: if (exponent_4 & ~ mask [exponent_bits]) {
280: /*
281: * Exponent overflow. Lose immediately.
282: */
283:
284: /*
285: * We leave return_value alone: admit we read the
286: * number, but return a floating exception
287: * because we can't encode the number.
288: */
289:
290: as_warn("Exponent overflow in floating-point number");
291: make_invalid_floating_point_number (words);
292: return return_value;
293: }
294: lp = words;
295:
296: /* Word 1. Sign, exponent and perhaps high bits. */
297: /* Assume 2's complement integers. */
298: word1 = ((exponent_4 & mask [exponent_bits]) << (15 - exponent_bits)) |
299: ((f.sign == '+') ? 0 : 0x8000) | next_bits (15 - exponent_bits,
300: &bits_left_in_littlenum, &littlenum_pointer);
301: * lp ++ = word1;
302:
303: /* The rest of the words are just mantissa bits. */
304: for (; lp < words + precision; lp++)
305: * lp = next_bits (LITTLENUM_NUMBER_OF_BITS,
306: &bits_left_in_littlenum, &littlenum_pointer);
307:
308: if (next_bits (1, &bits_left_in_littlenum, &littlenum_pointer)) {
309: unsigned long int carry;
310: /*
311: * Since the NEXT bit is a 1, round UP the mantissa.
312: * The cunning design of these hidden-1 floats permits
313: * us to let the mantissa overflow into the exponent, and
314: * it 'does the right thing'. However, we lose if the
315: * highest-order bit of the lowest-order word flips.
316: * Is that clear?
317: */
318:
319:
320: /* #if (sizeof(carry)) < ((sizeof(bits[0]) * BITS_PER_CHAR) + 2)
321: Please allow at least 1 more bit in carry than is in a LITTLENUM.
322: We need that extra bit to hold a carry during a LITTLENUM carry
323: propagation. Another extra bit (kept 0) will assure us that we
324: don't get a sticky sign bit after shifting right, and that
325: permits us to propagate the carry without any masking of bits.
326: #endif */
327: for (carry = 1, lp --; carry && (lp >= words); lp --) {
328: carry = * lp + carry;
329: * lp = carry;
330: carry >>= LITTLENUM_NUMBER_OF_BITS;
331: }
332: if ( (word1 ^ *words) & (1 << (LITTLENUM_NUMBER_OF_BITS - 1)) ) {
333: /* We leave return_value alone: admit we read the
334: * number, but return a floating exception
335: * because we can't encode the number.
336: */
337: make_invalid_floating_point_number (words);
338: return return_value;
339: }
340: }
341: return (return_value);
342: }
343:
344: gen_to_words(words,precision,exponent_bits)
345: LITTLENUM_TYPE *words;
346: long int exponent_bits;
347: {
348: int return_value=0;
349:
350: long int exponent_1;
351: long int exponent_2;
352: long int exponent_3;
353: long int exponent_4;
354: int exponent_skippage;
355: LITTLENUM_TYPE word1;
356: int bits_left_in_littlenum;
357: LITTLENUM_TYPE * littlenum_pointer;
358: LITTLENUM_TYPE * lp;
359:
360: if (generic_floating_point_number.low > generic_floating_point_number.leader) {
361: /* 0.0e0 seen. */
362: bzero (words, sizeof(LITTLENUM_TYPE) * precision);
363: return return_value;
364: }
365:
366: /*
367: * All vaxen floating_point formats (so far) have:
368: * Bit 15 is sign bit.
369: * Bits 14:n are excess-whatever exponent.
370: * Bits n-1:0 (if any) are most significant bits of fraction.
371: * Bits 15:0 of the next word are the next most significant bits.
372: * And so on for each other word.
373: *
374: * So we need: number of bits of exponent, number of bits of
375: * mantissa.
376: */
377: bits_left_in_littlenum = LITTLENUM_NUMBER_OF_BITS;
378: littlenum_pointer = generic_floating_point_number.leader;
379: /* Seek (and forget) 1st significant bit */
380: for (exponent_skippage = 0;! next_bits(1, &bits_left_in_littlenum,
381: &littlenum_pointer); exponent_skippage ++)
382: ;
383: exponent_1 = generic_floating_point_number.exponent + generic_floating_point_number.leader + 1 -
384: generic_floating_point_number.low;
385: /* Radix LITTLENUM_RADIX, point just higher than generic_floating_point_number.leader. */
386: exponent_2 = exponent_1 * LITTLENUM_NUMBER_OF_BITS;
387: /* Radix 2. */
388: exponent_3 = exponent_2 - exponent_skippage;
389: /* Forget leading zeros, forget 1st bit. */
390: exponent_4 = exponent_3 + ((1 << (exponent_bits - 1)) - 2);
391: /* Offset exponent. */
392:
393: if (exponent_4 & ~ mask [exponent_bits]) {
394: /*
395: * Exponent overflow. Lose immediately.
396: */
397:
398: /*
399: * We leave return_value alone: admit we read the
400: * number, but return a floating exception
401: * because we can't encode the number.
402: */
403:
404: make_invalid_floating_point_number (words);
405: return return_value;
406: }
407: lp = words;
408:
409: /* Word 1. Sign, exponent and perhaps high bits. */
410: /* Assume 2's complement integers. */
411: word1 = ((exponent_4 & mask [exponent_bits]) << (15 - exponent_bits)) |
412: ((generic_floating_point_number.sign == '+') ? 0 : 0x8000) | next_bits (15 - exponent_bits,
413: &bits_left_in_littlenum, &littlenum_pointer);
414: * lp ++ = word1;
415:
416: /* The rest of the words are just mantissa bits. */
417: for (; lp < words + precision; lp++)
418: * lp = next_bits (LITTLENUM_NUMBER_OF_BITS,
419: &bits_left_in_littlenum, &littlenum_pointer);
420:
421: if (next_bits (1, &bits_left_in_littlenum, &littlenum_pointer)) {
422: unsigned long int carry;
423: /*
424: * Since the NEXT bit is a 1, round UP the mantissa.
425: * The cunning design of these hidden-1 floats permits
426: * us to let the mantissa overflow into the exponent, and
427: * it 'does the right thing'. However, we lose if the
428: * highest-order bit of the lowest-order word flips.
429: * Is that clear?
430: */
431:
432:
433: /* #if (sizeof(carry)) < ((sizeof(bits[0]) * BITS_PER_CHAR) + 2)
434: Please allow at least 1 more bit in carry than is in a LITTLENUM.
435: We need that extra bit to hold a carry during a LITTLENUM carry
436: propagation. Another extra bit (kept 0) will assure us that we
437: don't get a sticky sign bit after shifting right, and that
438: permits us to propagate the carry without any masking of bits.
439: #endif */
440: for (carry = 1, lp --; carry && (lp >= words); lp --) {
441: carry = * lp + carry;
442: * lp = carry;
443: carry >>= LITTLENUM_NUMBER_OF_BITS;
444: }
445: if ( (word1 ^ *words) & (1 << (LITTLENUM_NUMBER_OF_BITS - 1)) ) {
446: /* We leave return_value alone: admit we read the
447: * number, but return a floating exception
448: * because we can't encode the number.
449: */
450: make_invalid_floating_point_number (words);
451: return return_value;
452: }
453: }
454: return (return_value);
455: }
456:
457: /* This routine is a real kludge. Someone really should do it better, but
458: I'm too lazy, and I don't understand this stuff all too well anyway
459: (JF)
460: */
461: int_to_gen(x)
462: long x;
463: {
464: char buf[20];
465: char *bufp;
466:
467: sprintf(buf,"%ld",x);
468: bufp= &buf[0];
469: if(atof_generic(&bufp,".", EXP_CHARS, &generic_floating_point_number))
470: as_warn("Error converting number to floating point (Exponent overflow?)");
471: }
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