1 /* Copyright © 2017 Keith Packard
2 All rights reserved.
3
4 Redistribution and use in source and binary forms, with or without
5 modification, are permitted provided that the following conditions are met:
6
7 * Redistributions of source code must retain the above copyright
8 notice, this list of conditions and the following disclaimer.
9 * Redistributions in binary form must reproduce the above copyright
10 notice, this list of conditions and the following disclaimer in
11 the documentation and/or other materials provided with the
12 distribution.
13 * Neither the name of the copyright holders nor the names of
14 contributors may be used to endorse or promote products derived
15 from this software without specific prior written permission.
16
17 THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
18 AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
21 LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
22 CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
23 SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
24 INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
25 CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
26 ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
27 POSSIBILITY OF SUCH DAMAGE. */
28
29 #if PRINTF_LEVEL < PRINTF_DBL && defined(_PRINTF_SMALL_ULTOA)
30
31 /*
32 * Enable fancy divmod for targets where we don't expect either
33 * hardware division support or that software will commonly be using
34 * the soft division code. That means platforms where 'long' is not at
35 * least 64-bits get the fancy code for 64-bit values and platforms
36 * where 'int' is not at least 32-bits also get the fancy code for
37 * 32-bit values
38 */
39
40 #if SIZEOF_ULTOA > __SIZEOF_LONG__
41
42 #define FANCY_DIVMOD
43
udivmod10(ultoa_unsigned_t n,char * rp)44 static inline ultoa_unsigned_t udivmod10(ultoa_unsigned_t n, char *rp) {
45 ultoa_unsigned_t q;
46 char r;
47
48 /* Compute n * 0x1999999999999999 / (2^64) ≃ n / 10 */
49
50 /* q = n * 0xc >> 4 */
51 q = (n >> 1) + (n >> 2);
52
53 /*
54 q = q * 0x11 >> 4
55 = (n * 0xc >> 4) * 0x11 >> 4
56 ≂ n * 0xcc >> 8
57 */
58 q = q + (q >> 4);
59
60 /*
61 q = q * 0x101 >> 8
62 = ((n * 0xc >> 4) * 0x11 >> 4) * 0x101 >> 8
63 ≂ (n * 0xcc >> 8) * 0x101 >> 8
64 ≂ n * 0xcccc >> 16
65 */
66 q = q + (q >> 8);
67
68 /*
69 q = q * 0x10001 >> 16
70 = (((n * 0xc >> 4) * 0x11 >> 4) * 0x101 >> 8) * 0x10001 >> 16
71 ≂ (n * 0xcccc >> 16) * 0x10001 >> 16
72 ≂ n * 0xcccccccc >> 32
73 */
74 q = q + (q >> 16);
75
76 #if SIZEOF_ULTOA > 4
77 /*
78 q = q * 0x100000001 >> 32
79 = ((((n * 0xc >> 4) * 0x11 >> 4) * 0x101 >> 8) * 0x10001 >> 16) * 0x100000001 >> 32
80 ≂ (n * 0xcccccccc >> 32) * 0x100000001 >> 32
81 ≂ n * cccccccccccccccc >> 64
82 */
83 q = q + (q >> 32);
84 #endif
85
86 /*
87 q = q >> 3
88 = (((((n * 0xc >> 4) * 0x11 >> 4) * 0x101 >> 8) * 0x10001 >> 16) * 0x100000001 >> 32) >> 3
89 ≂ (n * cccccccccccccccc >> 64) >> 3
90 ≂ n * 0x1999999999999999 >> 64
91 */
92 q = q >> 3;
93
94 /* r = n - q * 10 */
95 r = (char) (n - (((q << 2) + q) << 1));
96
97 /*
98 * Because of the approximations above, q will
99 * be +0/-1 of the real result. Check and adjust
100 */
101 if (r > 9) {
102 q++;
103 r -= 10;
104 }
105 *rp = r;
106 return q;
107 }
108
109 static inline ultoa_unsigned_t
udivmod(ultoa_unsigned_t val,int base,char * dig)110 udivmod(ultoa_unsigned_t val, int base, char *dig)
111 {
112 switch(base) {
113 #ifdef _WANT_IO_PERCENT_B
114 case 2:
115 *dig = val & 1;
116 return val >> 1;
117 #endif
118 case 8:
119 *dig = val & 7;
120 return val >> 3;
121 case 16:
122 *dig = val & 15;
123 return val >> 4;
124 }
125 return udivmod10(val, dig);
126 }
127
128 #endif
129 #endif
130
131 static __noinline char *
__ultoa_invert(ultoa_unsigned_t val,char * str,int base)132 __ultoa_invert(ultoa_unsigned_t val, char *str, int base)
133 {
134 char hex = ('a' - '0' - 10 + 16) - base;
135
136 base &= 31;
137
138 do {
139 char v;
140
141 #ifdef FANCY_DIVMOD
142 val = udivmod(val, base, &v);
143 #else
144 v = val % base;
145 val /= base;
146 #endif
147 if (v > 9)
148 v += hex;
149 v += '0';
150 *str++ = v;
151 } while (val);
152 return str;
153 }
154
