Hello,
Here's the test case for the suggested simple_strtoul function. I just
finished testing on a P3 where it seems to show a 16-20% speed improvement
over the current algorithm.
compile it as:
gcc /usr/src/linux/lib/ctype.c strtoul_test.c -o strtoul_test
You can change the numeric base value with this define to 8, 10, or 16 to
see the speed change for each numeric representation:
#define BASE 10
Have fun,
Steve Grubb
--strtoul_test.c--
#include unistd.h
#include stdlib.h
#include stdio.h
#include string.h
#include sys/resource.h
#include linux/ctype.h
struct timeval last_stopwatch_time;
void stopwatch()
{
struct timeval now;
int delta;
gettimeofday(now, 0);
delta = (now.tv_sec - last_stopwatch_time.tv_sec) * 100 +
(now.tv_usec - last_stopwatch_time.tv_usec);
printf ("Stopwatch: elapsed time %d.%03d seconds\n\n",
delta / 100, (delta / 1000) % 1000);
last_stopwatch_time = now;
}
unsigned long old_simple_strtoul(const char *cp,char **endp,unsigned int
base)
{
unsigned long result = 0,value;
if (!base) {
base = 10;
if (*cp == '0') {
base = 8;
cp++;
if ((*cp == 'x') isxdigit(cp[1])) {
cp++;
base = 16;
}
}
}
while (isxdigit(*cp) (value = isdigit(*cp) ? *cp-'0' : (islower(*cp)
? toupper(*cp) : *cp)-'A'+10) base) {
result = result*base + value;
cp++;
}
if (endp)
*endp = (char *)cp;
return result;
}
unsigned long new_simple_strtoul2(const char *cp,char **endp,unsigned int
base)
{
unsigned char c;
unsigned long result = 0;
if (!base) {
base = 10;
if (*cp == '0') {
base = 8;
cp++;
if ((*cp == 'x') isxdigit(cp[1])) {
cp++;
base = 16;
}
}
}
c = *cp;
switch (base) {
case 10:
while (isdigit(c)) {
result = (result*10) + (c 0x0f);
c = *(++cp);
}
break;
case 16:
while (isxdigit(c)) {
result = (result4);
if (c0x40)
result += (c 0x07) + 9;
else
result += (c 0x0f);
c = *(++cp);
}
break;
case 8:
while (isdigit(c)) {
if ((c0x37) == c)
result = (result3) + (c 0x07);
else
break;
c = *(++cp);
}
}
if (endp)
*endp = (char *)cp;
return result;
}
#define NUMBER_TO_TEST 32768
#define BASE 10
char f[3][3] = { "%d", "%X", "%o"};
char str[NUMBER_TO_TEST][32];
unsigned long r[NUMBER_TO_TEST];
int main()
{
int rn, i, j, iterations = 1000;
time_t tm;
time(tm);
srand((unsigned) tm);
rn = rand();
// do setup here
for (i=0; iNUMBER_TO_TEST; i++) {
r[i] = rand()%0x7FF;
switch (BASE) {
case 10:
sprintf(str[i][0], f[0][0], r[i]);
break;
case 16:
sprintf(str[i][0], f[1][0], r[i]);
break;
case 8:
sprintf(str[i][0], f[2][0], r[i]);
}
}
puts("Starting old algorithm");
sleep(5); // let the system settle down
gettimeofday(last_stopwatch_time, 0);
for (i=0; iiterations; i++) {
for (j=0; jNUMBER_TO_TEST; j++) {
old_simple_strtoul(str[j][0], NULL, BASE);
}
}
stopwatch();
puts("New algorithm");
sleep(5); // let the system settle down
gettimeofday(last_stopwatch_time, 0);
for (i=0; iiterations; i++) {
for (j=0; jNUMBER_TO_TEST; j++) {
new_simple_strtoul2(str[j][0], NULL, BASE);
}
}
stopwatch();
puts("Now checking values");
for (i=0; iNUMBER_TO_TEST; i++) {
unsigned long t = new_simple_strtoul2(str[i][0], NULL, BASE);
if (r[i] != t) {
switch (BASE) {
case 10:
printf("is %s conv %d\n", str[i][0], t);
break;
case 16:
printf("is %s conv %x\n", str[i][0], t);
break;
case 8:
printf("is %s conv %o\n", str[i][0], t);
}
break;
}
}
return 0;
}
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