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authorParamat <paramat@users.noreply.github.com>2018-04-21 22:50:36 +0100
committerGitHub <noreply@github.com>2018-04-21 22:50:36 +0100
commit12a8f8826d54362d70aae8524aa88118f2d84692 (patch)
tree86b1d7b5ac9d2091f8460f3ecf07e034371762a1 /src/clouds.cpp
parent5abd0efb903877efc2d6f4af571db400bc6551aa (diff)
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Mgvalleys: Use shared tunnel / cavern code instead of internal
Caverns first appeared in mgvalleys and were later added to other mapgens as shared code. Now this shared code can replace mgvalley's internal cavern code. Also use shared tunnel code instead of internal code. Changes to mapgen that will affect existing worlds (mgvalleys is not stable): Single lava and water sources not added in tunnels. Previous caverns are unchanged but an equal number of new ones are added at a distance from the previous. From y = -256 to 192 nodes below, where the caverns taper at their upper limit, they will have a slightly different shape as the taper is now linear.
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generated by cgit v1.2.3 (git 2.39.1) at 2025-01-13 18:37:45 +0000
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/*
 * Conversion of f32 to IEEE-754 and vice versa.
 *
 * © Copyright 2018 Pedro Gimeno Fortea.
 *
 * 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 AUTHORS OR COPYRIGHT HOLDERS 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.
 */
#include "ieee_float.h"
#include "log.h"
#include "porting.h"
#include <limits>
#include <cmath>

// Given an unsigned 32-bit integer representing an IEEE-754 single-precision
// float, return the float.
f32 u32Tof32Slow(u32 i)
{
	// clang-format off
	int exp = (i >> 23) & 0xFF;
	u32 sign = i & 0x80000000UL;
	u32 imant = i & 0x7FFFFFUL;
	if (exp == 0xFF) {
		// Inf/NaN
		if (imant == 0) {
			if (std::numeric_limits<f32>::has_infinity)	
				return sign ? -std::numeric_limits<f32>::infinity() :
					std::numeric_limits<f32>::infinity();
			return sign ? std::numeric_limits<f32>::max() :
				std::numeric_limits<f32>::lowest();
		}
		return std::numeric_limits<f32>::has_quiet_NaN ?
			std::numeric_limits<f32>::quiet_NaN() : -0.f;
	}

	if (!exp) {
		// Denormal or zero
		return sign ? -ldexpf((f32)imant, -149) : ldexpf((f32)imant, -149);
	}

	return sign ? -ldexpf((f32)(imant | 0x800000UL), exp - 150) :
		ldexpf((f32)(imant | 0x800000UL), exp - 150);
	// clang-format on
}

// Given a float, return an unsigned 32-bit integer representing the f32
// in IEEE-754 single-precision format.
u32 f32Tou32Slow(f32 f)
{
	u32 signbit = std::copysign(1.0f, f) == 1.0f ? 0 : 0x80000000UL;
	if (f == 0.f)
		return signbit;
	if (std::isnan(f))
		return signbit | 0x7FC00000UL;
	if (std::isinf(f))
		return signbit | 0x7F800000UL;
	int exp = 0; // silence warning
	f32 mant = frexpf(f, &exp);
	u32 imant = (u32)std::floor((signbit ? -16777216.f : 16777216.f) * mant);
	exp += 126;
	if (exp <= 0) {
		// Denormal
		return signbit | (exp <= -31 ? 0 : imant >> (1 - exp));
	}

	if (exp >= 255) {
		// Overflow due to the platform having exponents bigger than IEEE ones.
		// Return signed infinity.
		return signbit | 0x7F800000UL;
	}

	// Regular number
	return signbit | (exp << 23) | (imant & 0x7FFFFFUL);
}

// This test needs the following requisites in order to work:
// - The float type must be a 32 bits IEEE-754 single-precision float.
// - The endianness of f32s and integers must match.
FloatType getFloatSerializationType()
{
	// clang-format off
	const f32 cf = -22220490.f;
	const u32 cu = 0xCBA98765UL;
	if (std::numeric_limits<f32>::is_iec559 && sizeof(cf) == 4 &&
			sizeof(cu) == 4 && !memcmp(&cf, &cu, 4)) {
		// u32Tof32Slow and f32Tou32Slow are not needed, use memcpy
		return FLOATTYPE_SYSTEM;
	}

	// Run quick tests to ensure the custom functions provide acceptable results
	warningstream << "floatSerialization: f32 and u32 endianness are "
		"not equal or machine is not IEEE-754 compliant" << std::endl;
	u32 i;
	char buf[128];

	// NaN checks aren't included in the main loop