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
 29static 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
122static 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
182bool 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