/*
 * Copyright 2017 Advanced Micro Devices, Inc.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 *
 * Authors: AMD
 *
 */
#include "dm_services.h"
#include "custom_float.h"


static bool build_custom_float(
        struct fixed31_32 value,
        const struct custom_float_format *format,
        bool *negative,
        uint32_t *mantissa,
        uint32_t *exponenta)
{
        uint32_t exp_offset = (1 << (format->exponenta_bits - 1)) - 1;

        const struct fixed31_32 mantissa_constant_plus_max_fraction =
                dc_fixpt_from_fraction(
                        (1LL << (format->mantissa_bits + 1)) - 1,
                        1LL << format->mantissa_bits);

        struct fixed31_32 mantiss;

        if (dc_fixpt_eq(
                value,
                dc_fixpt_zero)) {
                *negative = false;
                *mantissa = 0;
                *exponenta = 0;
                return true;
        }

        if (dc_fixpt_lt(
                value,
                dc_fixpt_zero)) {
                *negative = format->sign;
                value = dc_fixpt_neg(value);
        } else {
                *negative = false;
        }

        if (dc_fixpt_lt(
                value,
                dc_fixpt_one)) {
                uint32_t i = 1;

                do {
                        value = dc_fixpt_shl(value, 1);
                        ++i;
                } while (dc_fixpt_lt(
                        value,
                        dc_fixpt_one));

                --i;

                if (exp_offset <= i) {
                        *mantissa = 0;
                        *exponenta = 0;
                        return true;
                }

                *exponenta = exp_offset - i;
        } else if (dc_fixpt_le(
                mantissa_constant_plus_max_fraction,
                value)) {
                uint32_t i = 1;

                do {
                        value = dc_fixpt_shr(value, 1);
                        ++i;
                } while (dc_fixpt_lt(
                        mantissa_constant_plus_max_fraction,
                        value));

                *exponenta = exp_offset + i - 1;
        } else {
                *exponenta = exp_offset;
        }

        mantiss = dc_fixpt_sub(
                value,
                dc_fixpt_one);

        if (dc_fixpt_lt(
                        mantiss,
                        dc_fixpt_zero) ||
                dc_fixpt_lt(
                        dc_fixpt_one,
                        mantiss))
                mantiss = dc_fixpt_zero;
        else
                mantiss = dc_fixpt_shl(
                        mantiss,
                        format->mantissa_bits);

        *mantissa = dc_fixpt_floor(mantiss);

        return true;
}

static bool setup_custom_float(
        const struct custom_float_format *format,
        bool negative,
        uint32_t mantissa,
        uint32_t exponenta,
        uint32_t *result)
{
        uint32_t i = 0;
        uint32_t j = 0;

        uint32_t value = 0;

        /* verification code:
         * once calculation is ok we can remove it
         */

        const uint32_t mantissa_mask =
                (1 << (format->mantissa_bits + 1)) - 1;

        const uint32_t exponenta_mask =
                (1 << (format->exponenta_bits + 1)) - 1;

        if (mantissa & ~mantissa_mask) {
                BREAK_TO_DEBUGGER();
                mantissa = mantissa_mask;
        }

        if (exponenta & ~exponenta_mask) {
                BREAK_TO_DEBUGGER();
                exponenta = exponenta_mask;
        }

        /* end of verification code */

        while (i < format->mantissa_bits) {
                uint32_t mask = 1 << i;

                if (mantissa & mask)
                        value |= mask;

                ++i;
        }

        while (j < format->exponenta_bits) {
                uint32_t mask = 1 << j;

                if (exponenta & mask)
                        value |= mask << i;

                ++j;
        }

        if (negative && format->sign)
                value |= 1 << (i + j);

        *result = value;

        return true;
}

bool convert_to_custom_float_format(
        struct fixed31_32 value,
        const struct custom_float_format *format,
        uint32_t *result)
{
        uint32_t mantissa;
        uint32_t exponenta;
        bool negative;

        return build_custom_float(
                value, format, &negative, &mantissa, &exponenta) &&
        setup_custom_float(
                format, negative, mantissa, exponenta, result);
}