1/* Decimal 32-bit format module for the decNumber C Library
2   Copyright (C) 2005 Free Software Foundation, Inc.
3   Contributed by IBM Corporation.  Author Mike Cowlishaw.
4
5   This file is part of GCC.
6
7   GCC is free software; you can redistribute it and/or modify it under
8   the terms of the GNU General Public License as published by the Free
9   Software Foundation; either version 2, or (at your option) any later
10   version.
11
12   In addition to the permissions in the GNU General Public License,
13   the Free Software Foundation gives you unlimited permission to link
14   the compiled version of this file into combinations with other
15   programs, and to distribute those combinations without any
16   restriction coming from the use of this file.  (The General Public
17   License restrictions do apply in other respects; for example, they
18   cover modification of the file, and distribution when not linked
19   into a combine executable.)
20
21   GCC is distributed in the hope that it will be useful, but WITHOUT ANY
22   WARRANTY; without even the implied warranty of MERCHANTABILITY or
23   FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
24   for more details.
25
26   You should have received a copy of the GNU General Public License
27   along with GCC; see the file COPYING.  If not, write to the Free
28   Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
29   02110-1301, USA.  */
30
31/* ------------------------------------------------------------------ */
32/* This module comprises the routines for decimal32 format numbers.   */
33/* Conversions are supplied to and from decNumber and String.         */
34/*                                                                    */
35/* No arithmetic routines are included; decNumber provides these.     */
36/*                                                                    */
37/* Error handling is the same as decNumber (qv.).                     */
38/* ------------------------------------------------------------------ */
39#include <string.h>		/* [for memset/memcpy] */
40#include <stdio.h>		/* [for printf] */
41
42#define  DECNUMDIGITS  7	/* we need decNumbers with space for 7 */
43#include "config.h"
44#include "decNumber.h"		/* base number library */
45#include "decNumberLocal.h"	/* decNumber local types, etc. */
46#include "decimal32.h"		/* our primary include */
47#include "decUtility.h"		/* utility routines */
48
49#if DECTRACE || DECCHECK
50void decimal32Show (const decimal32 *);	/* for debug */
51void decNumberShow (const decNumber *);	/* .. */
52#endif
53
54/* Useful macro */
55/* Clear a structure (e.g., a decNumber) */
56#define DEC_clear(d) memset(d, 0, sizeof(*d))
57
58/* ------------------------------------------------------------------ */
59/* decimal32FromNumber -- convert decNumber to decimal32              */
60/*                                                                    */
61/*   ds is the target decimal32                                       */
62/*   dn is the source number (assumed valid)                          */
63/*   set is the context, used only for reporting errors               */
64/*                                                                    */
65/* The set argument is used only for status reporting and for the     */
66/* rounding mode (used if the coefficient is more than DECIMAL32_Pmax */
67/* digits or an overflow is detected).  If the exponent is out of the */
68/* valid range then Overflow or Underflow will be raised.             */
69/* After Underflow a subnormal result is possible.                    */
70/*                                                                    */
71/* DEC_Clamped is set if the number has to be 'folded down' to fit,   */
72/* by reducing its exponent and multiplying the coefficient by a      */
73/* power of ten, or if the exponent on a zero had to be clamped.      */
74/* ------------------------------------------------------------------ */
75decimal32 *
76decimal32FromNumber (decimal32 * d32, const decNumber * dn, decContext * set)
77{
78  uInt status = 0;		/* status accumulator */
79  Int pad = 0;			/* coefficient pad digits */
80  decNumber dw;			/* work */
81  decContext dc;		/* .. */
82  uByte isneg = dn->bits & DECNEG;	/* non-0 if original sign set */
83  uInt comb, exp;		/* work */
84
85  /* If the number is finite, and has too many digits, or the exponent */
86  /* could be out of range then we reduce the number under the */
87  /* appropriate constraints */
88  if (!(dn->bits & DECSPECIAL))
89    {				/* not a special value */
90      Int ae = dn->exponent + dn->digits - 1;	/* adjusted exponent */
91      if (dn->digits > DECIMAL32_Pmax	/* too many digits */
92	  || ae > DECIMAL32_Emax	/* likely overflow */
93	  || ae < DECIMAL32_Emin)
94	{			/* likely underflow */
95	  decContextDefault (&dc, DEC_INIT_DECIMAL32);	/* [no traps] */
96	  dc.round = set->round;	/* use supplied rounding */
97	  decNumberPlus (&dw, dn, &dc);	/* (round and check) */
98	  /* [this changes -0 to 0, but it will be restored below] */
99	  status |= dc.status;	/* save status */
100	  dn = &dw;		/* use the work number */
101	}
102      /* [this could have pushed number to Infinity or zero, so this */
103      /* rounding must be done before we generate the decimal32] */
104    }
105
106  DEC_clear (d32);		/* clean the target */
107  if (dn->bits & DECSPECIAL)
108    {				/* a special value */
109      uByte top;		/* work */
110      if (dn->bits & DECINF)
111	top = DECIMAL_Inf;
112      else
113	{			/* sNaN or qNaN */
114	  if ((*dn->lsu != 0 || dn->digits > 1)	/* non-zero coefficient */
115	      && (dn->digits < DECIMAL32_Pmax))
116	    {			/* coefficient fits */
117	      decDensePackCoeff (dn, d32->bytes, sizeof (d32->bytes), 0);
118	    }
119	  if (dn->bits & DECNAN)
120	    top = DECIMAL_NaN;
121	  else
122	    top = DECIMAL_sNaN;
123	}
124      d32->bytes[0] = top;
125    }
126  else if (decNumberIsZero (dn))
127    {				/* a zero */
128      /* set and clamp exponent */
129      if (dn->exponent < -DECIMAL32_Bias)
130	{
131	  exp = 0;
132	  status |= DEC_Clamped;
133	}
134      else
135	{
136	  exp = dn->exponent + DECIMAL32_Bias;	/* bias exponent */
137	  if (exp > DECIMAL32_Ehigh)
138	    {			/* top clamp */
139	      exp = DECIMAL32_Ehigh;
140	      status |= DEC_Clamped;
141	    }
142	}
143      comb = (exp >> 3) & 0x18;	/* combination field */
144      d32->bytes[0] = (uByte) (comb << 2);
145      exp &= 0x3f;		/* remaining exponent bits */
146      decimal32SetExpCon (d32, exp);
147    }
148  else
149    {				/* non-zero finite number */
150      uInt msd;			/* work */
151
152      /* we have a dn that fits, but it may need to be padded */
153      exp = (uInt) (dn->exponent + DECIMAL32_Bias);	/* bias exponent */
154
155      if (exp > DECIMAL32_Ehigh)
156	{			/* fold-down case */
157	  pad = exp - DECIMAL32_Ehigh;
158	  exp = DECIMAL32_Ehigh;	/* [to maximum] */
159	  status |= DEC_Clamped;
160	}
161
162      decDensePackCoeff (dn, d32->bytes, sizeof (d32->bytes), pad);
163
164      /* save and clear the top digit */
165      msd = ((unsigned) d32->bytes[1] >> 4);
166      d32->bytes[1] &= 0x0f;
167      /* create the combination field */
168      if (msd >= 8)
169	comb = 0x18 | (msd & 0x01) | ((exp >> 5) & 0x06);
170      else
171	comb = (msd & 0x07) | ((exp >> 3) & 0x18);
172      d32->bytes[0] = (uByte) (comb << 2);
173      exp &= 0x3f;		/* remaining exponent bits */
174      decimal32SetExpCon (d32, exp);
175    }
176
177  if (isneg)
178    decimal32SetSign (d32, 1);
179  if (status != 0)
180    decContextSetStatus (set, status);	/* pass on status */
181
182  /*decimal32Show(d32); */
183  return d32;
184}
185
186/* ------------------------------------------------------------------ */
187/* decimal32ToNumber -- convert decimal32 to decNumber                */
188/*   d32 is the source decimal32                                      */
189/*   dn is the target number, with appropriate space                  */
190/* No error is possible.                                              */
191/* ------------------------------------------------------------------ */
192decNumber *
193decimal32ToNumber (const decimal32 * d32, decNumber * dn)
194{
195  uInt msd;			/* coefficient MSD */
196  decimal32 wk;			/* working copy, if needed */
197  uInt top = d32->bytes[0] & 0x7f;	/* top byte, less sign bit */
198  decNumberZero (dn);		/* clean target */
199  /* set the sign if negative */
200  if (decimal32Sign (d32))
201    dn->bits = DECNEG;
202
203  if (top >= 0x78)
204    {				/* is a special */
205      if ((top & 0x7c) == (DECIMAL_Inf & 0x7c))
206	dn->bits |= DECINF;
207      else if ((top & 0x7e) == (DECIMAL_NaN & 0x7e))
208	dn->bits |= DECNAN;
209      else
210	dn->bits |= DECSNAN;
211      msd = 0;			/* no top digit */
212    }
213  else
214    {				/* have a finite number */
215      uInt comb = top >> 2;	/* combination field */
216      uInt exp;			/* working exponent */
217
218      if (comb >= 0x18)
219	{
220	  msd = 8 + (comb & 0x01);
221	  exp = (comb & 0x06) << 5;	/* MSBs */
222	}
223      else
224	{
225	  msd = comb & 0x07;
226	  exp = (comb & 0x18) << 3;
227	}
228      dn->exponent = exp + decimal32ExpCon (d32) - DECIMAL32_Bias;	/* remove bias */
229    }
230
231  /* get the coefficient, unless infinite */
232  if (!(dn->bits & DECINF))
233    {
234      Int bunches = DECIMAL32_Pmax / 3;	/* coefficient full bunches to convert */
235      Int odd = 0;		/* assume MSD is 0 (no odd bunch) */
236      if (msd != 0)
237	{			/* coefficient has leading non-0 digit */
238	  /* make a copy of the decimal32, with an extra bunch which has */
239	  /* the top digit ready for conversion */
240	  wk = *d32;		/* take a copy */
241	  wk.bytes[0] = 0;	/* clear all but coecon */
242	  wk.bytes[1] &= 0x0f;	/* .. */
243	  wk.bytes[1] |= (msd << 4);	/* and prefix MSD */
244	  odd++;		/* indicate the extra */
245	  d32 = &wk;		/* use the work copy */
246	}
247      decDenseUnpackCoeff (d32->bytes, sizeof (d32->bytes), dn, bunches, odd);
248    }
249  return dn;
250}
251
252/* ------------------------------------------------------------------ */
253/* to-scientific-string -- conversion to numeric string               */
254/* to-engineering-string -- conversion to numeric string              */
255/*                                                                    */
256/*   decimal32ToString(d32, string);                                  */
257/*   decimal32ToEngString(d32, string);                               */
258/*                                                                    */
259/*  d32 is the decimal32 format number to convert                     */
260/*  string is the string where the result will be laid out            */
261/*                                                                    */
262/*  string must be at least 24 characters                             */
263/*                                                                    */
264/*  No error is possible, and no status can be set.                   */
265/* ------------------------------------------------------------------ */
266char *
267decimal32ToString (const decimal32 * d32, char *string)
268{
269  decNumber dn;			/* work */
270  decimal32ToNumber (d32, &dn);
271  decNumberToString (&dn, string);
272  return string;
273}
274
275char *
276decimal32ToEngString (const decimal32 * d32, char *string)
277{
278  decNumber dn;			/* work */
279  decimal32ToNumber (d32, &dn);
280  decNumberToEngString (&dn, string);
281  return string;
282}
283
284/* ------------------------------------------------------------------ */
285/* to-number -- conversion from numeric string                        */
286/*                                                                    */
287/*   decimal32FromString(result, string, set);                        */
288/*                                                                    */
289/*  result  is the decimal32 format number which gets the result of   */
290/*          the conversion                                            */
291/*  *string is the character string which should contain a valid      */
292/*          number (which may be a special value)                     */
293/*  set     is the context                                            */
294/*                                                                    */
295/* The context is supplied to this routine is used for error handling */
296/* (setting of status and traps) and for the rounding mode, only.     */
297/* If an error occurs, the result will be a valid decimal32 NaN.      */
298/* ------------------------------------------------------------------ */
299decimal32 *
300decimal32FromString (decimal32 * result, const char *string, decContext * set)
301{
302  decContext dc;		/* work */
303  decNumber dn;			/* .. */
304
305  decContextDefault (&dc, DEC_INIT_DECIMAL32);	/* no traps, please */
306  dc.round = set->round;	/* use supplied rounding */
307
308  decNumberFromString (&dn, string, &dc);	/* will round if needed */
309  decimal32FromNumber (result, &dn, &dc);
310  if (dc.status != 0)
311    {				/* something happened */
312      decContextSetStatus (set, dc.status);	/* .. pass it on */
313    }
314  return result;
315}
316
317#if DECTRACE || DECCHECK
318/* ------------------------------------------------------------------ */
319/* decimal32Show -- display a single in hexadecimal [debug aid]       */
320/*   d32 -- the number to show                                        */
321/* ------------------------------------------------------------------ */
322/* Also shows sign/cob/expconfields extracted */
323void
324decimal32Show (const decimal32 * d32)
325{
326  char buf[DECIMAL32_Bytes * 2 + 1];
327  Int i, j;
328  j = 0;
329  for (i = 0; i < DECIMAL32_Bytes; i++)
330    {
331      sprintf (&buf[j], "%02x", d32->bytes[i]);
332      j = j + 2;
333    }
334  printf (" D32> %s [S:%d Cb:%02x E:%d]\n", buf,
335	  decimal32Sign (d32), decimal32Comb (d32), decimal32ExpCon (d32));
336}
337#endif
338