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Member "memcached-1.6.15/itoa_ljust.c" (16 Jul 2020, 5242 Bytes) of package /linux/www/memcached-1.6.15.tar.gz:


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    1 //=== itoa_ljust.cpp - Fast integer to ascii conversion           --*- C++ -*-//
    2 //
    3 // Substantially simplified (and slightly faster) version
    4 // based on the following functions in Google's protocol buffers:
    5 //
    6 //    FastInt32ToBufferLeft()
    7 //    FastUInt32ToBufferLeft()
    8 //    FastInt64ToBufferLeft()
    9 //    FastUInt64ToBufferLeft()
   10 //
   11 // Differences:
   12 //    1) Greatly simplified
   13 //    2) Avoids GOTO statements - uses "switch" instead and relies on
   14 //       compiler constant folding and propagation for high performance
   15 //    3) Avoids unary minus of signed types - undefined behavior if value
   16 //       is INT_MIN in platforms using two's complement representation
   17 //    4) Uses memcpy to store 2 digits at a time - lets the compiler
   18 //       generate a 2-byte load/store in platforms that support
   19 //       unaligned access, this is faster (and less code) than explicitly
   20 //       loading and storing each byte
   21 //
   22 // Copyright (c) 2016 Arturo Martin-de-Nicolas
   23 // arturomdn@gmail.com
   24 // https://github.com/amdn/itoa_ljust/
   25 //
   26 // Released under the BSD 3-Clause License, see Google's original copyright
   27 // and license below.
   28 //===----------------------------------------------------------------------===//
   29 
   30 // Protocol Buffers - Google's data interchange format
   31 // Copyright 2008 Google Inc.  All rights reserved.
   32 // https://developers.google.com/protocol-buffers/
   33 //
   34 // Redistribution and use in source and binary forms, with or without
   35 // modification, are permitted provided that the following conditions are
   36 // met:
   37 //
   38 //     * Redistributions of source code must retain the above copyright
   39 // notice, this list of conditions and the following disclaimer.
   40 //     * Redistributions in binary form must reproduce the above
   41 // copyright notice, this list of conditions and the following disclaimer
   42 // in the documentation and/or other materials provided with the
   43 // distribution.
   44 //     * Neither the name of Google Inc. nor the names of its
   45 // contributors may be used to endorse or promote products derived from
   46 // this software without specific prior written permission.
   47 //
   48 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
   49 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
   50 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
   51 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
   52 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
   53 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
   54 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
   55 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
   56 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
   57 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
   58 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
   59 //===----------------------------------------------------------------------===//
   60 
   61 #include "itoa_ljust.h"
   62 #include <string.h>
   63 
   64 static const char lut[201] =
   65     "0001020304050607080910111213141516171819"
   66     "2021222324252627282930313233343536373839"
   67     "4041424344454647484950515253545556575859"
   68     "6061626364656667686970717273747576777879"
   69     "8081828384858687888990919293949596979899";
   70 
   71 #define dd(u) ((const uint16_t)(lut[u]))
   72 
   73 static inline char* out2(const int d, char* p) {
   74     memcpy(p, &((uint16_t *)lut)[d], 2);
   75     return p + 2;
   76 }
   77 
   78 static inline char* out1(const char in, char* p) {
   79     memcpy(p, &in, 1);
   80     return p + 1;
   81 }
   82 
   83 static inline int digits( uint32_t u, unsigned k, int* d, char** p, int n ) {
   84     if (u < k*10) {
   85         *d = u / k;
   86         *p = out1('0'+*d, *p);
   87         --n;
   88     }
   89     return n;
   90 }
   91 
   92 static inline char* itoa(uint32_t u, char* p, int d, int n) {
   93     switch(n) {
   94     case 10: d  = u / 100000000; p = out2( d, p );
   95     case  9: u -= d * 100000000;
   96     case  8: d  = u /   1000000; p = out2( d, p );
   97     case  7: u -= d *   1000000;
   98     case  6: d  = u /     10000; p = out2( d, p );
   99     case  5: u -= d *     10000;
  100     case  4: d  = u /       100; p = out2( d, p );
  101     case  3: u -= d *       100;
  102     case  2: d  = u /         1; p = out2( d, p );
  103     case  1: ;
  104     }
  105     *p = '\0';
  106     return p;
  107 }
  108 
  109 char* itoa_u32(uint32_t u, char* p) {
  110     int d = 0,n;
  111          if (u >=100000000) n = digits(u, 100000000, &d, &p, 10);
  112     else if (u <       100) n = digits(u,         1, &d, &p,  2);
  113     else if (u <     10000) n = digits(u,       100, &d, &p,  4);
  114     else if (u <   1000000) n = digits(u,     10000, &d, &p,  6);
  115     else                    n = digits(u,   1000000, &d, &p,  8);
  116     return itoa( u, p, d, n );
  117 }
  118 
  119 char* itoa_32(int32_t i, char* p) {
  120     uint32_t u = i;
  121     if (i < 0) {
  122         *p++ = '-';
  123         u = -u;
  124     }
  125     return itoa_u32(u, p);
  126 }
  127 
  128 char* itoa_u64(uint64_t u, char* p) {
  129     int d;
  130 
  131     uint32_t lower = (uint32_t)u;
  132     if (lower == u) return itoa_u32(lower, p);
  133 
  134     uint64_t upper = u / 1000000000;
  135     p = itoa_u64(upper, p);
  136     lower = u - (upper * 1000000000);
  137     d = lower / 100000000;
  138     p = out1('0'+d,p);
  139     return itoa( lower, p, d, 9 );
  140 }
  141 
  142 char* itoa_64(int64_t i, char* p) {
  143     uint64_t u = i;
  144     if (i < 0) {
  145         *p++ = '-';
  146         u = -u;
  147     }
  148     return itoa_u64(u, p);
  149 }