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utoa: shrink

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function                                             old     new   delta
itoa_to_buf                                           20      23      +3
utoa_to_buf                                          117     101     -16

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
Denys Vlasenko 2010-06-10 10:54:44 +02:00
parent 7fdf5a88b4
commit ab60cd1382
1 changed files with 29 additions and 15 deletions
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44
libbb/xfuncs.c
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@ -49,23 +49,35 @@ char* FAST_FUNC strncpy_IFNAMSIZ(char *dst, const char *src)
}
// Convert unsigned integer to ascii, writing into supplied buffer.
// A truncated result contains the first few digits of the result ala strncpy.
// Returns a pointer past last generated digit, does _not_ store NUL.
void BUG_sizeof_unsigned_not_4(void);
/* Convert unsigned integer to ascii, writing into supplied buffer.
* A truncated result contains the first few digits of the result ala strncpy.
* Returns a pointer past last generated digit, does _not_ store NUL.
*/
void BUG_sizeof(void);
char* FAST_FUNC utoa_to_buf(unsigned n, char *buf, unsigned buflen)
{
unsigned i, out, res;
if (sizeof(unsigned) != 4)
BUG_sizeof_unsigned_not_4();
if (buflen) {
out = 0;
for (i = 1000000000; i; i /= 10) {
if (sizeof(n) == 4)
// 2^32-1 = 4294967295
i = 1000000000;
#if UINT_MAX > 4294967295 /* prevents warning about "const too large" */
else
if (sizeof(n) == 8)
// 2^64-1 = 18446744073709551615
i = 10000000000000000000;
#endif
else
BUG_sizeof();
for (; i; i /= 10) {
res = n / i;
n = n % i;
if (res || out || i == 1) {
if (!--buflen) break;
if (--buflen == 0)
break;
out++;
n -= res*i;
*buf++ = '0' + res;
}
}
@ -76,7 +88,9 @@ char* FAST_FUNC utoa_to_buf(unsigned n, char *buf, unsigned buflen)
/* Convert signed integer to ascii, like utoa_to_buf() */
char* FAST_FUNC itoa_to_buf(int n, char *buf, unsigned buflen)
{
if (buflen && n < 0) {
if (!buflen)
return buf;
if (n < 0) {
n = -n;
*buf++ = '-';
buflen--;
@ -87,16 +101,16 @@ char* FAST_FUNC itoa_to_buf(int n, char *buf, unsigned buflen)
// The following two functions use a static buffer, so calling either one a
// second time will overwrite previous results.
//
// The largest 32 bit integer is -2 billion plus null terminator, or 12 bytes.
// It so happens that sizeof(int) * 3 is enough for 32+ bits.
// The largest 32 bit integer is -2 billion plus NUL, or 1+10+1=12 bytes.
// It so happens that sizeof(int) * 3 is enough for 32+ bit ints.
// (sizeof(int) * 3 + 2 is correct for any width, even 8-bit)
static char local_buf[sizeof(int) * 3];
// Convert unsigned integer to ascii using a static buffer (returned).
/* Convert unsigned integer to ascii using a static buffer (returned). */
char* FAST_FUNC utoa(unsigned n)
{
*(utoa_to_buf(n, local_buf, sizeof(local_buf))) = '\0';
*(utoa_to_buf(n, local_buf, sizeof(local_buf) - 1)) = '\0';
return local_buf;
}
@ -104,7 +118,7 @@ char* FAST_FUNC utoa(unsigned n)
/* Convert signed integer to ascii using a static buffer (returned). */
char* FAST_FUNC itoa(int n)
{
*(itoa_to_buf(n, local_buf, sizeof(local_buf))) = '\0';
*(itoa_to_buf(n, local_buf, sizeof(local_buf) - 1)) = '\0';
return local_buf;
}