1 /* Copyright 2022 Advanced Micro Devices, Inc.
2 *
3 * Permission is hereby granted, free of charge, to any person obtaining a
4 * copy of this software and associated documentation files (the "Software"),
5 * to deal in the Software without restriction, including without limitation
6 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
7 * and/or sell copies of the Software, and to permit persons to whom the
8 * Software is furnished to do so, subject to the following conditions:
9 *
10 * The above copyright notice and this permission notice shall be included in
11 * all copies or substantial portions of the Software.
12 *
13 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
14 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
15 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
16 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
17 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
18 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
19 * OTHER DEALINGS IN THE SOFTWARE.
20 *
21 * Authors: AMD
22 *
23 */
24 #include "custom_float.h"
25
build_custom_float(struct fixed31_32 value,const struct custom_float_format * format,bool * negative,uint32_t * mantissa,uint32_t * exponenta)26 static bool build_custom_float(struct fixed31_32 value, const struct custom_float_format *format,
27 bool *negative, uint32_t *mantissa, uint32_t *exponenta)
28 {
29 uint32_t exp_offset = (1 << (format->exponenta_bits - 1)) - 1;
30
31 const struct fixed31_32 mantissa_constant_plus_max_fraction = vpe_fixpt_from_fraction(
32 (1LL << (format->mantissa_bits + 1)) - 1, 1LL << format->mantissa_bits);
33
34 struct fixed31_32 mantiss;
35
36 if (vpe_fixpt_eq(value, vpe_fixpt_zero)) {
37 *negative = false;
38 *mantissa = 0;
39 *exponenta = 0;
40 return true;
41 }
42
43 if (vpe_fixpt_lt(value, vpe_fixpt_zero)) {
44 *negative = format->sign;
45 value = vpe_fixpt_neg(value);
46 } else {
47 *negative = false;
48 }
49
50 if (vpe_fixpt_lt(value, vpe_fixpt_one)) {
51 uint32_t i = 1;
52
53 do {
54 value = vpe_fixpt_shl(value, 1);
55 ++i;
56 } while (vpe_fixpt_lt(value, vpe_fixpt_one));
57
58 --i;
59
60 if (exp_offset <= i) {
61 *mantissa = 0;
62 *exponenta = 0;
63 return true;
64 }
65
66 *exponenta = exp_offset - i;
67 } else if (vpe_fixpt_le(mantissa_constant_plus_max_fraction, value)) {
68 uint32_t i = 1;
69
70 do {
71 value = vpe_fixpt_shr(value, 1);
72 ++i;
73 } while (vpe_fixpt_lt(mantissa_constant_plus_max_fraction, value));
74
75 *exponenta = exp_offset + i - 1;
76 } else {
77 *exponenta = exp_offset;
78 }
79
80 mantiss = vpe_fixpt_sub(value, vpe_fixpt_one);
81
82 if (vpe_fixpt_lt(mantiss, vpe_fixpt_zero) || vpe_fixpt_lt(vpe_fixpt_one, mantiss))
83 mantiss = vpe_fixpt_zero;
84 else
85 mantiss = vpe_fixpt_shl(mantiss, (unsigned char)format->mantissa_bits);
86
87 *mantissa = (uint32_t)vpe_fixpt_floor(mantiss);
88
89 return true;
90 }
91
setup_custom_float(const struct custom_float_format * format,bool negative,uint32_t mantissa,uint32_t exponenta,uint32_t * result)92 static bool setup_custom_float(const struct custom_float_format *format, bool negative,
93 uint32_t mantissa, uint32_t exponenta, uint32_t *result)
94 {
95 uint32_t i = 0;
96 uint32_t j = 0;
97
98 uint32_t value = 0;
99
100 /* verification code:
101 * once calculation is ok we can remove it
102 */
103
104 const uint32_t mantissa_mask = (1 << (format->mantissa_bits + 1)) - 1;
105
106 const uint32_t exponenta_mask = (1 << (format->exponenta_bits + 1)) - 1;
107
108 if (mantissa & ~mantissa_mask) {
109 VPE_ASSERT(0);
110 mantissa = mantissa_mask;
111 }
112
113 if (exponenta & ~exponenta_mask) {
114 VPE_ASSERT(0);
115 exponenta = exponenta_mask;
116 }
117
118 /* end of verification code */
119
120 while (i < format->mantissa_bits) {
121 uint32_t mask = 1 << i;
122
123 if (mantissa & mask)
124 value |= mask;
125
126 ++i;
127 }
128
129 while (j < format->exponenta_bits) {
130 uint32_t mask = 1 << j;
131
132 if (exponenta & mask)
133 value |= mask << i;
134
135 ++j;
136 }
137
138 if (negative && format->sign)
139 value |= 1 << (i + j);
140
141 *result = value;
142
143 return true;
144 }
145
vpe_convert_to_custom_float_format(struct fixed31_32 value,const struct custom_float_format * format,uint32_t * result)146 bool vpe_convert_to_custom_float_format(
147 struct fixed31_32 value, const struct custom_float_format *format, uint32_t *result)
148 {
149 uint32_t mantissa;
150 uint32_t exponenta;
151 bool negative;
152
153 return build_custom_float(value, format, &negative, &mantissa, &exponenta) &&
154 setup_custom_float(format, negative, mantissa, exponenta, result);
155 }
156