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/**
* slibc — Yet another C library
* Copyright © 2015 Mattias Andrée (maandree@member.fsf.org)
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <stdio.h>
#include <string.h>
#include <time.h>
/**
* Used to determine the signness of `char`.
*/
volatile char nul = 0;
/**
* Used to determine the signness of `wchar_t`.
*
* Note that `wchar_t` is set implicitly by the
* help of the compiler so that our libc does
* not taint the result.
*/
volatile typeof(L'\0') wnul = 0;
/**
* On my amd64 machine, the usual result is:
* int_fast8_t = int32_t
* int_fast16_t = int32_t
* int_fast32_t = int32_t
* int_fast64_t = int64_t
*/
/**
* Measure the performance of a intrinsic integer type,
* and if it is faster than the previous candidate (or
* is the first candidate,) store it as the, yet, most
* performant candidate.
*
* @param VAR A volatile register variable of the
* type that shall be tested.
*/
#define FAST_TEST(VAR) \
n = 0, *VAR##p = 0; \
if (clock_gettime(CLOCK_THREAD_CPUTIME_ID, &start)) \
return perror(""), -1; \
for (;;) \
{ \
for (m = 1000; m--;) \
VAR = 50, VAR += 50, VAR -= 50, VAR *= 50, VAR /= 50, VAR <<= 1, VAR >>= 1, *VAR##p |= 1; \
n++; \
if (clock_gettime(CLOCK_THREAD_CPUTIME_ID, &end)) \
return perror(""), -1; \
if (end.tv_sec > start.tv_sec + 2) \
break; \
if (end.tv_sec > start.tv_sec + 1) \
if (end.tv_nsec >= start.tv_nsec) \
break; \
} \
time_elapsed = (long long int)(end.tv_sec) * 1000000000LL; \
time_elapsed += (long long int)(end.tv_nsec); \
time_elapsed -= (long long int)(start.tv_sec) * 1000000000LL; \
time_elapsed -= (long long int)(start.tv_nsec); \
adjn = (double)n, adjn /= (double)time_elapsed / 1000000000.; \
fprintf(stderr, "int%zu_t:%s %i000 op:s in %lli.%09lli s = %lf op:s/s\n", \
8 * sizeof(VAR), 8 * sizeof(VAR) < 10 ? " " : "", 8 * n, \
time_elapsed / 1000000000LL, time_elapsed % 1000000000LL, adjn * 8000.); \
if ((!best) || (adjn > bestn)) \
bestn = adjn, best = 8 * sizeof(VAR); \
last = this
/**
* Determine whether the performance of `typeof(VAR)` should be determined,
* when finding the most performant, compatiable intrinsic type of a `int_fastN_t`.
*
* @param VAR An variable of the type (or the type itself) that is a candidate.
* @return Determine whether the type shall be tested.
*/
#define TEST(VAR) (this = 8 * (int)sizeof(VAR), ((this >= bits) && (this > last)))
#if defined(__GNUC__)
__attribute__((optimize("-O0")))
#endif
/**
* Find the (in general) fastest intrinsic integer type,
* that has at least a specified number of bits.
*
* @param bits The minimum number of bits the type may have.
* @return The number of bits the most performance
* compatible integer type has.
*/
static int fast(int bits)
{
int last = 0, this = 0, best = 0, n, m;
float bestn = 0;
float adjn;
struct timespec start, end;
long long int time_elapsed;
register volatile char hhi;
register volatile short int hi;
register volatile int i;
register volatile long int li;
register volatile long long int lli;
volatile char hhip[1];
volatile short int hip[1];
volatile int ip[1];
volatile long int lip[1];
volatile long long int llip[1];
if (TEST(hhi)) { FAST_TEST(hhi); }
if (TEST(hi)) { FAST_TEST(hi); }
if (TEST(i)) { FAST_TEST(i); }
if (TEST(li)) { FAST_TEST(li); }
if (best) {
if (TEST(lli)) { FAST_TEST(lli); }
} else
best = 64;
fprintf(stderr, "int_fast%i_t = int%i_t\n\n", bits, best);
return best;
}
#undef TEST
/**
* @param argc The number of command line arguments, should
* be either 1 (print integer width information)
* or 2 (otherwise).
* @param argv Command line arguments, if `argc == 2`, `argv[2]`
* is interpreted as follows:
* - "fast8" Print the number of bits in `int_fast8_t` and `uint_fast8_t`.
* - "fast16" Print the number of bits in `int_fast16_t` and `uint_fast16_t`.
* - "fast32" Print the number of bits in `int_fast32_t` and `uint_fast32_t`.
* - "fast64" Print the number of bits in `int_fast64_t` and `uint_fast64_t`.
* - "char-signed" Print 1 if `char` is signed, and `0` if it is unsigned.
* - "wchar-signed" Print 1 if `wchar_t` is signed, and `0` if it is unsigned.
* @return 0 on success, 1 on error (including printing error.)
*/
int main(int argc, char* argv[])
{
int r = 0;
if (argc < 2)
{
/* Print the number of bits in the intrinsic integers types. */
r |= printf("CHAR_BIT %zu\n", 8 * sizeof(char));
r |= printf("SHORT_BIT %zu\n", 8 * sizeof(short int));
r |= printf("INT_BIT %zu\n", 8 * sizeof(int));
r |= printf("LONG_BIT %zu\n", 8 * sizeof(long int));
r |= printf("LONG_LONG_BIT %zu\n", 8 * sizeof(long long int));
r |= printf("PTR_BIT %zu\n", 8 * sizeof(void*));
r |= printf("WCHAR_BIT %zu\n", 8 * sizeof(L'\0'));
/* Print the intrinsic type for specific numbers of bits. */
r |= printf("INT%zu %s\n", 8 * sizeof(char), "char");
r |= printf("INT%zu %s\n", 8 * sizeof(short int), "short int");
r |= printf("INT%zu %s\n", 8 * sizeof(int), "int");
r |= printf("INT%zu %s\n", 8 * sizeof(long int), "long int");
r |= printf("INT%zu %s\n", 8 * sizeof(long long int), "long long int");
return r < 0 ? 1 : 0;
}
else if (argc == 2)
{
if (!strcmp(argv[1], "fast8")) r = fast(8);
else if (!strcmp(argv[1], "fast16")) r = fast(16);
else if (!strcmp(argv[1], "fast32")) r = fast(32);
else if (!strcmp(argv[1], "fast64")) r = fast(64);
else if (!strcmp(argv[1], "char-signed"))
{
nul = ~nul;
r = !(nul > 0);
return printf("%i\n", r) < 0 ? 1 : 0;
}
else if (!strcmp(argv[1], "wchar-signed"))
{
wnul = ~wnul;
r = !(wnul > 0);
return printf("%i\n", r) < 0 ? 1 : 0;
}
if (r <= 0)
return 1;
return printf("%i\n", r) < 0 ? 1 : 0;
}
return 1;
}
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