1 /*
2  * Copyright 2017 Advanced Micro Devices, Inc.
3  *
4  * Permission is hereby granted, free of charge, to any person obtaining a
5  * copy of this software and associated documentation files (the "Software"),
6  * to deal in the Software without restriction, including without limitation
7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
8  * and/or sell copies of the Software, and to permit persons to whom the
9  * Software is furnished to do so, subject to the following conditions:
10  *
11  * The above copyright notice and this permission notice shall be included in
12  * all copies or substantial portions of the Software.
13  *
14  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
15  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
16  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
17  * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
18  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
19  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
20  * OTHER DEALINGS IN THE SOFTWARE.
21  *
22  * Authors: AMD
23  *
24  */
25 #include "dm_services.h"
26 #include "custom_float.h"
27 
28 
build_custom_float(struct fixed31_32 value,const struct custom_float_format * format,bool * negative,uint32_t * mantissa,uint32_t * exponenta)29 static bool build_custom_float(
30 	struct fixed31_32 value,
31 	const struct custom_float_format *format,
32 	bool *negative,
33 	uint32_t *mantissa,
34 	uint32_t *exponenta)
35 {
36 	uint32_t exp_offset = (1 << (format->exponenta_bits - 1)) - 1;
37 
38 	const struct fixed31_32 mantissa_constant_plus_max_fraction =
39 		dc_fixpt_from_fraction(
40 			(1LL << (format->mantissa_bits + 1)) - 1,
41 			1LL << format->mantissa_bits);
42 
43 	struct fixed31_32 mantiss;
44 
45 	if (dc_fixpt_eq(
46 		value,
47 		dc_fixpt_zero)) {
48 		*negative = false;
49 		*mantissa = 0;
50 		*exponenta = 0;
51 		return true;
52 	}
53 
54 	if (dc_fixpt_lt(
55 		value,
56 		dc_fixpt_zero)) {
57 		*negative = format->sign;
58 		value = dc_fixpt_neg(value);
59 	} else {
60 		*negative = false;
61 	}
62 
63 	if (dc_fixpt_lt(
64 		value,
65 		dc_fixpt_one)) {
66 		uint32_t i = 1;
67 
68 		do {
69 			value = dc_fixpt_shl(value, 1);
70 			++i;
71 		} while (dc_fixpt_lt(
72 			value,
73 			dc_fixpt_one));
74 
75 		--i;
76 
77 		if (exp_offset <= i) {
78 			*mantissa = 0;
79 			*exponenta = 0;
80 			return true;
81 		}
82 
83 		*exponenta = exp_offset - i;
84 	} else if (dc_fixpt_le(
85 		mantissa_constant_plus_max_fraction,
86 		value)) {
87 		uint32_t i = 1;
88 
89 		do {
90 			value = dc_fixpt_shr(value, 1);
91 			++i;
92 		} while (dc_fixpt_lt(
93 			mantissa_constant_plus_max_fraction,
94 			value));
95 
96 		*exponenta = exp_offset + i - 1;
97 	} else {
98 		*exponenta = exp_offset;
99 	}
100 
101 	mantiss = dc_fixpt_sub(
102 		value,
103 		dc_fixpt_one);
104 
105 	if (dc_fixpt_lt(
106 			mantiss,
107 			dc_fixpt_zero) ||
108 		dc_fixpt_lt(
109 			dc_fixpt_one,
110 			mantiss))
111 		mantiss = dc_fixpt_zero;
112 	else
113 		mantiss = dc_fixpt_shl(
114 			mantiss,
115 			format->mantissa_bits);
116 
117 	*mantissa = dc_fixpt_floor(mantiss);
118 
119 	return true;
120 }
121 
setup_custom_float(const struct custom_float_format * format,bool negative,uint32_t mantissa,uint32_t exponenta,uint32_t * result)122 static bool setup_custom_float(
123 	const struct custom_float_format *format,
124 	bool negative,
125 	uint32_t mantissa,
126 	uint32_t exponenta,
127 	uint32_t *result)
128 {
129 	uint32_t i = 0;
130 	uint32_t j = 0;
131 
132 	uint32_t value = 0;
133 
134 	/* verification code:
135 	 * once calculation is ok we can remove it
136 	 */
137 
138 	const uint32_t mantissa_mask =
139 		(1 << (format->mantissa_bits + 1)) - 1;
140 
141 	const uint32_t exponenta_mask =
142 		(1 << (format->exponenta_bits + 1)) - 1;
143 
144 	if (mantissa & ~mantissa_mask) {
145 		BREAK_TO_DEBUGGER();
146 		mantissa = mantissa_mask;
147 	}
148 
149 	if (exponenta & ~exponenta_mask) {
150 		BREAK_TO_DEBUGGER();
151 		exponenta = exponenta_mask;
152 	}
153 
154 	/* end of verification code */
155 
156 	while (i < format->mantissa_bits) {
157 		uint32_t mask = 1 << i;
158 
159 		if (mantissa & mask)
160 			value |= mask;
161 
162 		++i;
163 	}
164 
165 	while (j < format->exponenta_bits) {
166 		uint32_t mask = 1 << j;
167 
168 		if (exponenta & mask)
169 			value |= mask << i;
170 
171 		++j;
172 	}
173 
174 	if (negative && format->sign)
175 		value |= 1 << (i + j);
176 
177 	*result = value;
178 
179 	return true;
180 }
181 
convert_to_custom_float_format(struct fixed31_32 value,const struct custom_float_format * format,uint32_t * result)182 bool convert_to_custom_float_format(
183 	struct fixed31_32 value,
184 	const struct custom_float_format *format,
185 	uint32_t *result)
186 {
187 	uint32_t mantissa;
188 	uint32_t exponenta;
189 	bool negative;
190 
191 	return build_custom_float(
192 		value, format, &negative, &mantissa, &exponenta) &&
193 	setup_custom_float(
194 		format, negative, mantissa, exponenta, result);
195 }
196 
197 
198