common.h
// Copyright 2018 Ulf Adams
//
// The contents of this file may be used under the terms of the Apache License,
// Version 2.0.
//
// (See accompanying file LICENSE-Apache or copy at
// http://www.apache.org/licenses/LICENSE-2.0)
//
// Alternatively, the contents of this file may be used under the terms of
// the Boost Software License, Version 1.0.
// (See accompanying file LICENSE-Boost or copy at
// https://www.boost.org/LICENSE_1_0.txt)
//
// Unless required by applicable law or agreed to in writing, this software
// is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
// KIND, either express or implied.
#ifndef RYU_COMMON_H
#define RYU_COMMON_H
#include <assert.h>
#include <stdint.h>
#include <string.h>
#if defined(_M_IX86) || defined(_M_ARM)
#define RYU_32_BIT_PLATFORM
#endif
// Returns the number of decimal digits in v, which must not contain more than 9 digits.
static inline uint32_t decimalLength9(const uint32_t v) {
// Function precondition: v is not a 10-digit number.
// (f2s: 9 digits are sufficient for round-tripping.)
// (d2fixed: We print 9-digit blocks.)
assert(v >= 0);
assert(v < 1000000000);
if (v >= 100000000) { return 9; }
if (v >= 10000000) { return 8; }
if (v >= 1000000) { return 7; }
if (v >= 100000) { return 6; }
if (v >= 10000) { return 5; }
if (v >= 1000) { return 4; }
if (v >= 100) { return 3; }
if (v >= 10) { return 2; }
return 1;
}
// Returns e == 0 ? 1 : ceil(log_2(5^e)); requires 0 <= e <= 3528.
static inline int32_t pow5bits(const int32_t e) {
// This approximation works up to the point that the multiplication overflows at e = 3529.
// If the multiplication were done in 64 bits, it would fail at 5^4004 which is just greater
// than 2^9297.
assert(e >= 0);
assert(e <= 3528);
return (int32_t) (((((uint32_t) e) * 1217359) >> 19) + 1);
}
// Returns e == 0 ? 1 : ceil(log_2(5^e)); requires 0 <= e <= 3528.
static inline int32_t ceil_log2pow5(const int32_t e) {
return pow5bits(e);
}
// Returns floor(log_10(2^e)); requires 0 <= e <= 1650.
static inline uint32_t log10Pow2(const int32_t e) {
// The first value this approximation fails for is 2^1651 which is just greater than 10^297.
assert(e >= 0);
assert(e <= 1650);
return (((uint32_t) e) * 78913) >> 18;
}
// Returns floor(log_10(5^e)); requires 0 <= e <= 2620.
static inline uint32_t log10Pow5(const int32_t e) {
// The first value this approximation fails for is 5^2621 which is just greater than 10^1832.
assert(e >= 0);
assert(e <= 2620);
return (((uint32_t) e) * 732923) >> 20;
}
static inline int copy_special_str(char * const result, const bool sign, const bool exponent, const bool mantissa) {
if (mantissa) {
memcpy(result, "NaN", 3);
return 3;
}
if (exponent) {
/* PostGIS: Do not print signed zero */
if (sign) {
result[0] = '-';
}
memcpy(result + sign, "Infinity", 8);
return sign + 8;
}
memcpy(result, "0", 1);
return 1;
}
static inline uint32_t float_to_bits(const float f) {
uint32_t bits = 0;
memcpy(&bits, &f, sizeof(float));
return bits;
}
static inline uint64_t double_to_bits(const double d) {
uint64_t bits = 0;
memcpy(&bits, &d, sizeof(double));
return bits;
}
#endif // RYU_COMMON_H