//=== 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);

}