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| 1 /* | |
| 2 ** 2013-06-10 | |
| 3 ** | |
| 4 ** The author disclaims copyright to this source code. In place of | |
| 5 ** a legal notice, here is a blessing: | |
| 6 ** | |
| 7 ** May you do good and not evil. | |
| 8 ** May you find forgiveness for yourself and forgive others. | |
| 9 ** May you share freely, never taking more than you give. | |
| 10 ** | |
| 11 ************************************************************************* | |
| 12 ** This file contains a simple command-line utility for converting from | |
| 13 ** integers and LogEst values and back again and for doing simple | |
| 14 ** arithmetic operations (multiple and add) on LogEst values. | |
| 15 ** | |
| 16 ** Usage: | |
| 17 ** | |
| 18 ** ./LogEst ARGS | |
| 19 ** | |
| 20 ** See the showHelp() routine for a description of valid arguments. | |
| 21 ** Examples: | |
| 22 ** | |
| 23 ** To convert 123 from LogEst to integer: | |
| 24 ** | |
| 25 ** ./LogEst ^123 | |
| 26 ** | |
| 27 ** To convert 123456 from integer to LogEst: | |
| 28 ** | |
| 29 ** ./LogEst 123456 | |
| 30 ** | |
| 31 */ | |
| 32 #include <stdio.h> | |
| 33 #include <stdlib.h> | |
| 34 #include <ctype.h> | |
| 35 #include <assert.h> | |
| 36 #include <string.h> | |
| 37 #include "sqlite3.h" | |
| 38 | |
| 39 typedef short int LogEst; /* 10 times log2() */ | |
| 40 | |
| 41 LogEst logEstMultiply(LogEst a, LogEst b){ return a+b; } | |
| 42 LogEst logEstAdd(LogEst a, LogEst b){ | |
| 43 static const unsigned char x[] = { | |
| 44 10, 10, /* 0,1 */ | |
| 45 9, 9, /* 2,3 */ | |
| 46 8, 8, /* 4,5 */ | |
| 47 7, 7, 7, /* 6,7,8 */ | |
| 48 6, 6, 6, /* 9,10,11 */ | |
| 49 5, 5, 5, /* 12-14 */ | |
| 50 4, 4, 4, 4, /* 15-18 */ | |
| 51 3, 3, 3, 3, 3, 3, /* 19-24 */ | |
| 52 2, 2, 2, 2, 2, 2, 2, /* 25-31 */ | |
| 53 }; | |
| 54 if( a<b ){ LogEst t = a; a = b; b = t; } | |
| 55 if( a>b+49 ) return a; | |
| 56 if( a>b+31 ) return a+1; | |
| 57 return a+x[a-b]; | |
| 58 } | |
| 59 LogEst logEstFromInteger(sqlite3_uint64 x){ | |
| 60 static LogEst a[] = { 0, 2, 3, 5, 6, 7, 8, 9 }; | |
| 61 LogEst y = 40; | |
| 62 if( x<8 ){ | |
| 63 if( x<2 ) return 0; | |
| 64 while( x<8 ){ y -= 10; x <<= 1; } | |
| 65 }else{ | |
| 66 while( x>255 ){ y += 40; x >>= 4; } | |
| 67 while( x>15 ){ y += 10; x >>= 1; } | |
| 68 } | |
| 69 return a[x&7] + y - 10; | |
| 70 } | |
| 71 static sqlite3_uint64 logEstToInt(LogEst x){ | |
| 72 sqlite3_uint64 n; | |
| 73 if( x<10 ) return 1; | |
| 74 n = x%10; | |
| 75 x /= 10; | |
| 76 if( n>=5 ) n -= 2; | |
| 77 else if( n>=1 ) n -= 1; | |
| 78 if( x>=3 ) return (n+8)<<(x-3); | |
| 79 return (n+8)>>(3-x); | |
| 80 } | |
| 81 static LogEst logEstFromDouble(double x){ | |
| 82 sqlite3_uint64 a; | |
| 83 LogEst e; | |
| 84 assert( sizeof(x)==8 && sizeof(a)==8 ); | |
| 85 if( x<=0.0 ) return -32768; | |
| 86 if( x<0.01 ) return -logEstFromDouble(1.0/x); | |
| 87 if( x<1.0 ) return logEstFromDouble(100.0*x) - 66; | |
| 88 if( x<1024.0 ) return logEstFromInteger((sqlite3_uint64)(1024.0*x)) - 100; | |
| 89 if( x<=2000000000.0 ) return logEstFromInteger((sqlite3_uint64)x); | |
| 90 memcpy(&a, &x, 8); | |
| 91 e = (a>>52) - 1022; | |
| 92 return e*10; | |
| 93 } | |
| 94 | |
| 95 int isInteger(const char *z){ | |
| 96 while( z[0]>='0' && z[0]<='9' ) z++; | |
| 97 return z[0]==0; | |
| 98 } | |
| 99 | |
| 100 int isFloat(const char *z){ | |
| 101 char c; | |
| 102 while( ((c=z[0])>='0' && c<='9') || c=='.' || c=='E' || c=='e' | |
| 103 || c=='+' || c=='-' ) z++; | |
| 104 return z[0]==0; | |
| 105 } | |
| 106 | |
| 107 static void showHelp(const char *zArgv0){ | |
| 108 printf("Usage: %s ARGS...\n", zArgv0); | |
| 109 printf("Arguments:\n" | |
| 110 " NUM Convert NUM from integer to LogEst and push onto the stack\n" | |
| 111 " ^NUM Interpret NUM as a LogEst and push onto stack\n" | |
| 112 " x Multiple the top two elements of the stack\n" | |
| 113 " + Add the top two elements of the stack\n" | |
| 114 " dup Dupliate the top element on the stack\n" | |
| 115 " inv Take the reciprocal of the top of stack. N = 1/N.\n" | |
| 116 " log Find the LogEst of the number on top of stack\n" | |
| 117 " nlogn Compute NlogN where N is the top of stack\n" | |
| 118 ); | |
| 119 exit(1); | |
| 120 } | |
| 121 | |
| 122 int main(int argc, char **argv){ | |
| 123 int i; | |
| 124 int n = 0; | |
| 125 LogEst a[100]; | |
| 126 for(i=1; i<argc; i++){ | |
| 127 const char *z = argv[i]; | |
| 128 if( strcmp(z,"+")==0 ){ | |
| 129 if( n>=2 ){ | |
| 130 a[n-2] = logEstAdd(a[n-2],a[n-1]); | |
| 131 n--; | |
| 132 } | |
| 133 }else if( strcmp(z,"x")==0 ){ | |
| 134 if( n>=2 ){ | |
| 135 a[n-2] = logEstMultiply(a[n-2],a[n-1]); | |
| 136 n--; | |
| 137 } | |
| 138 }else if( strcmp(z,"dup")==0 ){ | |
| 139 if( n>0 ){ | |
| 140 a[n] = a[n-1]; | |
| 141 n++; | |
| 142 } | |
| 143 }else if( strcmp(z,"log")==0 ){ | |
| 144 if( n>0 ) a[n-1] = logEstFromInteger(a[n-1]) - 33; | |
| 145 }else if( strcmp(z,"nlogn")==0 ){ | |
| 146 if( n>0 ) a[n-1] += logEstFromInteger(a[n-1]) - 33; | |
| 147 }else if( strcmp(z,"inv")==0 ){ | |
| 148 if( n>0 ) a[n-1] = -a[n-1]; | |
| 149 }else if( z[0]=='^' ){ | |
| 150 a[n++] = atoi(z+1); | |
| 151 }else if( isInteger(z) ){ | |
| 152 a[n++] = logEstFromInteger(atoi(z)); | |
| 153 }else if( isFloat(z) && z[0]!='-' ){ | |
| 154 a[n++] = logEstFromDouble(atof(z)); | |
| 155 }else{ | |
| 156 showHelp(argv[0]); | |
| 157 } | |
| 158 } | |
| 159 for(i=n-1; i>=0; i--){ | |
| 160 if( a[i]<-40 ){ | |
| 161 printf("%5d (%f)\n", a[i], 1.0/(double)logEstToInt(-a[i])); | |
| 162 }else if( a[i]<10 ){ | |
| 163 printf("%5d (%f)\n", a[i], logEstToInt(a[i]+100)/1024.0); | |
| 164 }else{ | |
| 165 sqlite3_uint64 x = logEstToInt(a[i]+100)*100/1024; | |
| 166 printf("%5d (%lld.%02lld)\n", a[i], x/100, x%100); | |
| 167 } | |
| 168 } | |
| 169 return 0; | |
| 170 } | |
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Chromium Code Reviews
Issue 2363173002:
[sqlite] Remove obsolete reference version 3.8.7.4. (Closed)
