1/* Copyright (C) 2007-2022 Free Software Foundation, Inc.
2
3This file is part of GCC.
4
5GCC is free software; you can redistribute it and/or modify it under
6the terms of the GNU General Public License as published by the Free
7Software Foundation; either version 3, or (at your option) any later
8version.
9
10GCC is distributed in the hope that it will be useful, but WITHOUT ANY
11WARRANTY; without even the implied warranty of MERCHANTABILITY or
12FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
13for more details.
14
15Under Section 7 of GPL version 3, you are granted additional
16permissions described in the GCC Runtime Library Exception, version
173.1, as published by the Free Software Foundation.
18
19You should have received a copy of the GNU General Public License and
20a copy of the GCC Runtime Library Exception along with this program;
21see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
22<http://www.gnu.org/licenses/>.  */
23
24#include "bid_internal.h"
25
26#define MAX_FORMAT_DIGITS     16
27#define DECIMAL_EXPONENT_BIAS 398
28#define MAX_DECIMAL_EXPONENT  767
29
30#if DECIMAL_CALL_BY_REFERENCE
31
32void
33bid64_quantize (UINT64 * pres, UINT64 * px,
34		UINT64 *
35		py _RND_MODE_PARAM _EXC_FLAGS_PARAM _EXC_MASKS_PARAM
36		_EXC_INFO_PARAM) {
37  UINT64 x, y;
38#else
39
40UINT64
41bid64_quantize (UINT64 x,
42		UINT64 y _RND_MODE_PARAM _EXC_FLAGS_PARAM
43		_EXC_MASKS_PARAM _EXC_INFO_PARAM) {
44#endif
45  UINT128 CT;
46  UINT64 sign_x, sign_y, coefficient_x, coefficient_y, remainder_h, C64,
47    valid_x;
48  UINT64 tmp, carry, res;
49  int_float tempx;
50  int exponent_x, exponent_y, digits_x, extra_digits, amount, amount2;
51  int expon_diff, total_digits, bin_expon_cx;
52  unsigned rmode, status;
53
54#if DECIMAL_CALL_BY_REFERENCE
55#if !DECIMAL_GLOBAL_ROUNDING
56  _IDEC_round rnd_mode = *prnd_mode;
57#endif
58  x = *px;
59  y = *py;
60#endif
61
62  valid_x = unpack_BID64 (&sign_x, &exponent_x, &coefficient_x, x);
63  // unpack arguments, check for NaN or Infinity
64  if (!unpack_BID64 (&sign_y, &exponent_y, &coefficient_y, y)) {
65    // Inf. or NaN or 0
66#ifdef SET_STATUS_FLAGS
67    if ((x & SNAN_MASK64) == SNAN_MASK64)	// y is sNaN
68      __set_status_flags (pfpsf, INVALID_EXCEPTION);
69#endif
70
71    // x=Inf, y=Inf?
72    if (((coefficient_x << 1) == 0xf000000000000000ull)
73	&& ((coefficient_y << 1) == 0xf000000000000000ull)) {
74      res = coefficient_x;
75      BID_RETURN (res);
76    }
77    // Inf or NaN?
78    if ((y & 0x7800000000000000ull) == 0x7800000000000000ull) {
79#ifdef SET_STATUS_FLAGS
80      if (((y & 0x7e00000000000000ull) == 0x7e00000000000000ull)	// sNaN
81	  || (((y & 0x7c00000000000000ull) == 0x7800000000000000ull) &&	//Inf
82	      ((x & 0x7c00000000000000ull) < 0x7800000000000000ull)))
83	__set_status_flags (pfpsf, INVALID_EXCEPTION);
84#endif
85      if ((y & NAN_MASK64) != NAN_MASK64)
86	coefficient_y = 0;
87      if ((x & NAN_MASK64) != NAN_MASK64) {
88	res = 0x7c00000000000000ull | (coefficient_y & QUIET_MASK64);
89	if (((y & NAN_MASK64) != NAN_MASK64) && ((x & NAN_MASK64) == 0x7800000000000000ull))
90		res = x;
91	BID_RETURN (res);
92      }
93    }
94  }
95  // unpack arguments, check for NaN or Infinity
96  if (!valid_x) {
97    // x is Inf. or NaN or 0
98
99    // Inf or NaN?
100    if ((x & 0x7800000000000000ull) == 0x7800000000000000ull) {
101#ifdef SET_STATUS_FLAGS
102      if (((x & 0x7e00000000000000ull) == 0x7e00000000000000ull)	// sNaN
103	  || ((x & 0x7c00000000000000ull) == 0x7800000000000000ull))	//Inf
104	__set_status_flags (pfpsf, INVALID_EXCEPTION);
105#endif
106      if ((x & NAN_MASK64) != NAN_MASK64)
107	coefficient_x = 0;
108      res = 0x7c00000000000000ull | (coefficient_x & QUIET_MASK64);
109      BID_RETURN (res);
110    }
111
112    res = very_fast_get_BID64_small_mantissa (sign_x, exponent_y, 0);
113    BID_RETURN (res);
114  }
115  // get number of decimal digits in coefficient_x
116  tempx.d = (float) coefficient_x;
117  bin_expon_cx = ((tempx.i >> 23) & 0xff) - 0x7f;
118  digits_x = estimate_decimal_digits[bin_expon_cx];
119  if (coefficient_x >= power10_table_128[digits_x].w[0])
120    digits_x++;
121
122  expon_diff = exponent_x - exponent_y;
123  total_digits = digits_x + expon_diff;
124
125  // check range of scaled coefficient
126  if ((UINT32) (total_digits + 1) <= 17) {
127    if (expon_diff >= 0) {
128      coefficient_x *= power10_table_128[expon_diff].w[0];
129      res = very_fast_get_BID64 (sign_x, exponent_y, coefficient_x);
130      BID_RETURN (res);
131    }
132    // must round off -expon_diff digits
133    extra_digits = -expon_diff;
134#ifndef IEEE_ROUND_NEAREST_TIES_AWAY
135#ifndef IEEE_ROUND_NEAREST
136    rmode = rnd_mode;
137    if (sign_x && (unsigned) (rmode - 1) < 2)
138      rmode = 3 - rmode;
139#else
140    rmode = 0;
141#endif
142#else
143    rmode = 0;
144#endif
145    coefficient_x += round_const_table[rmode][extra_digits];
146
147    // get P*(2^M[extra_digits])/10^extra_digits
148    __mul_64x64_to_128 (CT, coefficient_x,
149			reciprocals10_64[extra_digits]);
150
151    // now get P/10^extra_digits: shift C64 right by M[extra_digits]-128
152    amount = short_recip_scale[extra_digits];
153    C64 = CT.w[1] >> amount;
154#ifndef IEEE_ROUND_NEAREST_TIES_AWAY
155#ifndef IEEE_ROUND_NEAREST
156    if (rnd_mode == 0)
157#endif
158      if (C64 & 1) {
159	// check whether fractional part of initial_P/10^extra_digits
160	// is exactly .5
161	// this is the same as fractional part of
162	//   (initial_P + 0.5*10^extra_digits)/10^extra_digits is exactly zero
163
164	// get remainder
165	amount2 = 64 - amount;
166	remainder_h = 0;
167	remainder_h--;
168	remainder_h >>= amount2;
169	remainder_h = remainder_h & CT.w[1];
170
171	// test whether fractional part is 0
172	if (!remainder_h && (CT.w[0] < reciprocals10_64[extra_digits])) {
173	  C64--;
174	}
175      }
176#endif
177
178#ifdef SET_STATUS_FLAGS
179    status = INEXACT_EXCEPTION;
180    // get remainder
181    remainder_h = CT.w[1] << (64 - amount);
182    switch (rmode) {
183    case ROUNDING_TO_NEAREST:
184    case ROUNDING_TIES_AWAY:
185      // test whether fractional part is 0
186      if ((remainder_h == 0x8000000000000000ull)
187	  && (CT.w[0] < reciprocals10_64[extra_digits]))
188	status = EXACT_STATUS;
189      break;
190    case ROUNDING_DOWN:
191    case ROUNDING_TO_ZERO:
192      if (!remainder_h && (CT.w[0] < reciprocals10_64[extra_digits]))
193	status = EXACT_STATUS;
194      //if(!C64 && rmode==ROUNDING_DOWN) sign_s=sign_y;
195      break;
196    default:
197      // round up
198      __add_carry_out (tmp, carry, CT.w[0],
199		       reciprocals10_64[extra_digits]);
200      if ((remainder_h >> (64 - amount)) + carry >=
201	  (((UINT64) 1) << amount))
202	status = EXACT_STATUS;
203      break;
204    }
205    __set_status_flags (pfpsf, status);
206#endif
207
208    res = very_fast_get_BID64_small_mantissa (sign_x, exponent_y, C64);
209    BID_RETURN (res);
210  }
211
212  if (total_digits < 0) {
213#ifdef SET_STATUS_FLAGS
214    __set_status_flags (pfpsf, INEXACT_EXCEPTION);
215#endif
216    C64 = 0;
217#ifndef IEEE_ROUND_NEAREST_TIES_AWAY
218#ifndef IEEE_ROUND_NEAREST
219    rmode = rnd_mode;
220    if (sign_x && (unsigned) (rmode - 1) < 2)
221      rmode = 3 - rmode;
222    if (rmode == ROUNDING_UP)
223      C64 = 1;
224#endif
225#endif
226    res = very_fast_get_BID64_small_mantissa (sign_x, exponent_y, C64);
227    BID_RETURN (res);
228  }
229  // else  more than 16 digits in coefficient
230#ifdef SET_STATUS_FLAGS
231  __set_status_flags (pfpsf, INVALID_EXCEPTION);
232#endif
233  res = 0x7c00000000000000ull;
234  BID_RETURN (res);
235
236}
237