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/* ScummVM - Graphic Adventure Engine
*
* ScummVM is the legal property of its developers, whose names
* are too numerous to list here. Please refer to the COPYRIGHT
* file distributed with this source distribution.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
*/
#include "glk/glulxe/glulxe.h"
namespace Glk {
namespace Glulxe {
uint Glulxe::encode_float(gfloat32 val) {
gfloat32 absval;
uint sign;
int expo;
gfloat32 mant;
uint fbits;
if (signbit(val)) {
sign = 0x80000000;
absval = -val;
} else {
sign = 0x0;
absval = val;
}
if (isinf(val)) {
return sign | 0x7f800000; /* infinity */
}
if (isnan(val)) {
return sign | 0x7fc00000;
}
mant = frexpf(absval, &expo);
/* Normalize mantissa to be in the range [1.0, 2.0) */
if (0.5 <= mant && mant < 1.0) {
mant *= 2.0;
expo--;
} else if (mant == 0.0) {
expo = 0;
} else {
return sign | 0x7f800000; /* infinity */
}
if (expo >= 128) {
return sign | 0x7f800000; /* infinity */
} else if (expo < -126) {
/* Denormalized (very small) number */
mant = ldexpf(mant, 126 + expo);
expo = 0;
} else if (!(expo == 0 && mant == 0.0)) {
expo += 127;
mant -= 1.0; /* Get rid of leading 1 */
}
mant *= 8388608.0; /* 2^23 */
fbits = (uint)(mant + 0.5); /* round mant to nearest int */
if (fbits >> 23) {
/* The carry propagated out of a string of 23 1 bits. */
fbits = 0;
expo++;
if (expo >= 255) {
return sign | 0x7f800000; /* infinity */
}
}
return (sign) | ((uint)(expo << 23)) | (fbits);
}
gfloat32 Glulxe::decode_float(uint val) {
int sign;
int expo;
uint mant;
gfloat32 res;
/* First byte */
sign = ((val & 0x80000000) != 0);
expo = (val >> 23) & 0xFF;
mant = val & 0x7FFFFF;
if (expo == 255) {
if (mant == 0) {
/* Infinity */
return (sign ? (-INFINITY) : (INFINITY));
} else {
/* Not a number */
return (sign ? (-NAN) : (NAN));
}
}
res = (gfloat32)mant / 8388608.0;
if (expo == 0) {
expo = -126;
} else {
res += 1.0;
expo -= 127;
}
res = ldexpf(res, expo);
return (sign ? (-res) : (res));
}
} // End of namespace Glulxe
} // End of namespace Glk
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