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//=== itoa_ljust.cpp - Fast integer to ascii conversion --*- C++ -*-//
//
// Substantially simplified (and slightly faster) version
// based on the following functions in Google's protocol buffers:
//
// FastInt32ToBufferLeft()
// FastUInt32ToBufferLeft()
// FastInt64ToBufferLeft()
// FastUInt64ToBufferLeft()
//
// Differences:
// 1) Greatly simplified
// 2) Avoids GOTO statements - uses "switch" instead and relies on
// compiler constant folding and propagation for high performance
// 3) Avoids unary minus of signed types - undefined behavior if value
// is INT_MIN in platforms using two's complement representation
// 4) Uses memcpy to store 2 digits at a time - lets the compiler
// generate a 2-byte load/store in platforms that support
// unaligned access, this is faster (and less code) than explicitly
// loading and storing each byte
//
// Copyright (c) 2016 Arturo Martin-de-Nicolas
// arturomdn@gmail.com
// https://github.com/amdn/itoa_ljust/
//
// Released under the BSD 3-Clause License, see Google's original copyright
// and license below.
//===----------------------------------------------------------------------===//
// Protocol Buffers - Google's data interchange format
// Copyright 2008 Google Inc. All rights reserved.
// https://developers.google.com/protocol-buffers/
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
//===----------------------------------------------------------------------===//
#include "itoa_ljust.h"
#include <string.h>
static const char lut[201] =
"0001020304050607080910111213141516171819"
"2021222324252627282930313233343536373839"
"4041424344454647484950515253545556575859"
"6061626364656667686970717273747576777879"
"8081828384858687888990919293949596979899";
#define dd(u) ((const uint16_t)(lut[u]))
static inline char* out2(const int d, char* p) {
memcpy(p, &((uint16_t *)lut)[d], 2);
return p + 2;
}
static inline char* out1(const char in, char* p) {
memcpy(p, &in, 1);
return p + 1;
}
static inline int digits( uint32_t u, unsigned k, int* d, char** p, int n ) {
if (u < k*10) {
*d = u / k;
*p = out1('0'+*d, *p);
--n;
}
return n;
}
static inline char* itoa(uint32_t u, char* p, int d, int n) {
switch(n) {
case 10: d = u / 100000000; p = out2( d, p );
case 9: u -= d * 100000000;
case 8: d = u / 1000000; p = out2( d, p );
case 7: u -= d * 1000000;
case 6: d = u / 10000; p = out2( d, p );
case 5: u -= d * 10000;
case 4: d = u / 100; p = out2( d, p );
case 3: u -= d * 100;
case 2: d = u / 1; p = out2( d, p );
case 1: ;
}
*p = '\0';
return p;
}
char* itoa_u32(uint32_t u, char* p) {
int d = 0,n;
if (u >=100000000) n = digits(u, 100000000, &d, &p, 10);
else if (u < 100) n = digits(u, 1, &d, &p, 2);
else if (u < 10000) n = digits(u, 100, &d, &p, 4);
else if (u < 1000000) n = digits(u, 10000, &d, &p, 6);
else n = digits(u, 1000000, &d, &p, 8);
return itoa( u, p, d, n );
}
char* itoa_32(int32_t i, char* p) {
uint32_t u = i;
if (i < 0) {
*p++ = '-';
u = -u;
}
return itoa_u32(u, p);
}
char* itoa_u64(uint64_t u, char* p) {
int d;
uint32_t lower = (uint32_t)u;
if (lower == u) return itoa_u32(lower, p);
uint64_t upper = u / 1000000000;
p = itoa_u64(upper, p);
lower = u - (upper * 1000000000);
d = lower / 100000000;
p = out1('0'+d,p);
return itoa( lower, p, d, 9 );
}
char* itoa_64(int64_t i, char* p) {
uint64_t u = i;
if (i < 0) {
*p++ = '-';
u = -u;
}
return itoa_u64(u, p);
}
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