Skip to content

Instantly share code, notes, and snippets.

@zed zed/main.c
Created Apr 18, 2010

Embed
What would you like to do?
compare relative performance of tolower_ctype, tolower_openbsd, tolower_oraz functions
// compare relative performance of tolower_ctype, tolower_openbsd, tolower_oraz functions
// result: 30.80, 30.51, 38.09
// $ gcc -std=c99 -O3 -g -Wall -pedantic test_tolower.c -o test_tolower;
// $ valgrind --tool=callgrind ./test_tolower 1000000
#include <assert.h>
#include <ctype.h>
#include <inttypes.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
static const char chars[] = { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33,
34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52,
53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71,
72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90,
91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107,
108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122,
123, 124, 125, 126, 127, '\0'
};
static const int nchars = sizeof(chars) / sizeof(*chars);
typedef char* (*fun_t)(char*);
static intptr_t test(int N, fun_t tolower_) {
char *str = malloc(nchars+1);
if (!str) {
perror("malloc");
exit(1);
}
str = strncpy(str, chars, nchars);
str[nchars] = '\0';
for (int i = 0; i < N; ++i)
tolower_(str);
free(str);
return (intptr_t)str;
}
static char* tolower_oraz(char* str) {
char *p = str;
for ( ; *p; ++p) *p = *p >= 'A' && *p <= 'Z' ? *p|0x60 : *p;
return p;
}
static char* tolower_ctype(char* str) {
char *p = str;
for ( ; *p; ++p) *p = tolower(*p);
return p;
}
static const short _C_tolower_[] = {
EOF,
0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07,
0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17,
0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27,
0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f,
0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37,
0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f,
0x40, 'a', 'b', 'c', 'd', 'e', 'f', 'g',
'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o',
'p', 'q', 'r', 's', 't', 'u', 'v', 'w',
'x', 'y', 'z', 0x5b, 0x5c, 0x5d, 0x5e, 0x5f,
0x60, 0x61, 0x62, 0x63, 0x64, 0x65, 0x66, 0x67,
0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d, 0x6e, 0x6f,
0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77,
0x78, 0x79, 0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f,
0x80, 0x81, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87,
0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e, 0x8f,
0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97,
0x98, 0x99, 0x9a, 0x9b, 0x9c, 0x9d, 0x9e, 0x9f,
0xa0, 0xa1, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7,
0xa8, 0xa9, 0xaa, 0xab, 0xac, 0xad, 0xae, 0xaf,
0xb0, 0xb1, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6, 0xb7,
0xb8, 0xb9, 0xba, 0xbb, 0xbc, 0xbd, 0xbe, 0xbf,
0xc0, 0xc1, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7,
0xc8, 0xc9, 0xca, 0xcb, 0xcc, 0xcd, 0xce, 0xcf,
0xd0, 0xd1, 0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7,
0xd8, 0xd9, 0xda, 0xdb, 0xdc, 0xdd, 0xde, 0xdf,
0xe0, 0xe1, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7,
0xe8, 0xe9, 0xea, 0xeb, 0xec, 0xed, 0xee, 0xef,
0xf0, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7,
0xf8, 0xf9, 0xfa, 0xfb, 0xfc, 0xfd, 0xfe, 0xff
};
static const short *tbl_C_tolower_ = _C_tolower_;
static int _tolower_openbsd(int c) {
// assert(c >= -1);
return c > 255 ? c : (tbl_C_tolower_+1)[c];
}
static char* tolower_openbsd(char* str) {
char *p = str;
for ( ; *p; ++p) *p = _tolower_openbsd(*p);
return p;
}
int main(int argc, char *argv[]) {
const int N = argc <= 1 ? 1000000 : atoi(argv[1]);
fun_t funcs[] = { tolower_ctype, tolower_oraz, tolower_openbsd };
const int nfuncs = sizeof(funcs) / sizeof(*funcs);
for (fun_t *pf = funcs; pf != &funcs[nfuncs]; ++pf)
printf("%" PRIxPTR "\n", test(N, *pf));
return 0;
}
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
You can’t perform that action at this time.