1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
|
/*
* Copyright (c) 2017-2019, ARM Limited and Contributors. All rights reserved.
*
* SPDX-License-Identifier: BSD-3-Clause
*/
/*
* Form ABI specifications:
* int __aeabi_idiv(int numerator, int denominator);
* unsigned __aeabi_uidiv(unsigned numerator, unsigned denominator);
*
* typedef struct { int quot; int rem; } idiv_return;
* typedef struct { unsigned quot; unsigned rem; } uidiv_return;
*
* __value_in_regs idiv_return __aeabi_idivmod(int numerator,
* int *denominator);
* __value_in_regs uidiv_return __aeabi_uidivmod(unsigned *numerator,
* unsigned denominator);
*/
/* struct qr - stores quotient/remainder to handle divmod EABI interfaces. */
struct qr {
unsigned int q; /* computed quotient */
unsigned int r; /* computed remainder */
unsigned int q_n; /* specifies if quotient shall be negative */
unsigned int r_n; /* specifies if remainder shall be negative */
};
static void uint_div_qr(unsigned int numerator, unsigned int denominator,
struct qr *qr);
/* returns in R0 and R1 by tail calling an asm function */
unsigned int __aeabi_uidivmod(unsigned int numerator, unsigned int denominator);
unsigned int __aeabi_uidiv(unsigned int numerator, unsigned int denominator);
/* returns in R0 and R1 by tail calling an asm function */
signed int __aeabi_idivmod(signed int numerator, signed int denominator);
signed int __aeabi_idiv(signed int numerator, signed int denominator);
/*
* __ste_idivmod_ret_t __aeabi_idivmod(signed numerator, signed denominator)
* Numerator and Denominator are received in R0 and R1.
* Where __ste_idivmod_ret_t is returned in R0 and R1.
*
* __ste_uidivmod_ret_t __aeabi_uidivmod(unsigned numerator,
* unsigned denominator)
* Numerator and Denominator are received in R0 and R1.
* Where __ste_uidivmod_ret_t is returned in R0 and R1.
*/
#ifdef __GNUC__
signed int ret_idivmod_values(signed int quotient, signed int remainder);
unsigned int ret_uidivmod_values(unsigned int quotient, unsigned int remainder);
#else
#error "Compiler not supported"
#endif
static void division_qr(unsigned int n, unsigned int p, struct qr *qr)
{
unsigned int i = 1, q = 0;
if (p == 0) {
qr->r = 0xFFFFFFFF; /* division by 0 */
return;
}
while ((p >> 31) == 0) {
i = i << 1; /* count the max division steps */
p = p << 1; /* increase p until it has maximum size*/
}
while (i > 0) {
q = q << 1; /* write bit in q at index (size-1) */
if (n >= p) {
n -= p;
q++;
}
p = p >> 1; /* decrease p */
i = i >> 1; /* decrease remaining size in q */
}
qr->r = n;
qr->q = q;
}
static void uint_div_qr(unsigned int numerator, unsigned int denominator,
struct qr *qr)
{
division_qr(numerator, denominator, qr);
/* negate quotient and/or remainder according to requester */
if (qr->q_n)
qr->q = -qr->q;
if (qr->r_n)
qr->r = -qr->r;
}
unsigned int __aeabi_uidiv(unsigned int numerator, unsigned int denominator)
{
struct qr qr = { .q_n = 0, .r_n = 0 };
uint_div_qr(numerator, denominator, &qr);
return qr.q;
}
unsigned int __aeabi_uidivmod(unsigned int numerator, unsigned int denominator)
{
struct qr qr = { .q_n = 0, .r_n = 0 };
uint_div_qr(numerator, denominator, &qr);
return ret_uidivmod_values(qr.q, qr.r);
}
signed int __aeabi_idiv(signed int numerator, signed int denominator)
{
struct qr qr = { .q_n = 0, .r_n = 0 };
if (((numerator < 0) && (denominator > 0)) ||
((numerator > 0) && (denominator < 0)))
qr.q_n = 1; /* quotient shall be negate */
if (numerator < 0) {
numerator = -numerator;
qr.r_n = 1; /* remainder shall be negate */
}
if (denominator < 0)
denominator = -denominator;
uint_div_qr(numerator, denominator, &qr);
return qr.q;
}
signed int __aeabi_idivmod(signed int numerator, signed int denominator)
{
struct qr qr = { .q_n = 0, .r_n = 0 };
if (((numerator < 0) && (denominator > 0)) ||
((numerator > 0) && (denominator < 0)))
qr.q_n = 1; /* quotient shall be negate */
if (numerator < 0) {
numerator = -numerator;
qr.r_n = 1; /* remainder shall be negate */
}
if (denominator < 0)
denominator = -denominator;
uint_div_qr(numerator, denominator, &qr);
return ret_idivmod_values(qr.q, qr.r);
}
|
