[STRING_UNITS_10] = 1000,
[STRING_UNITS_2] = 1024,
};
- int i, j;
- u32 remainder = 0, sf_cap, exp;
+ static const unsigned int rounding[] = { 500, 50, 5 };
+ int i = 0, j;
+ u32 remainder = 0, sf_cap;
char tmp[8];
const char *unit;
tmp[0] = '\0';
- i = 0;
- if (!size)
+
+ if (blk_size == 0)
+ size = 0;
+ if (size == 0)
goto out;
- while (blk_size >= divisor[units]) {
- remainder = do_div(blk_size, divisor[units]);
+ /* This is Napier's algorithm. Reduce the original block size to
+ *
+ * coefficient * divisor[units]^i
+ *
+ * we do the reduction so both coefficients are just under 32 bits so
+ * that multiplying them together won't overflow 64 bits and we keep
+ * as much precision as possible in the numbers.
+ *
+ * Note: it's safe to throw away the remainders here because all the
+ * precision is in the coefficients.
+ */
+ while (blk_size >> 32) {
+ do_div(blk_size, divisor[units]);
i++;
}
- exp = divisor[units] / (u32)blk_size;
- if (size >= exp) {
- remainder = do_div(size, divisor[units]);
- remainder *= blk_size;
+ while (size >> 32) {
+ do_div(size, divisor[units]);
i++;
- } else {
- remainder *= size;
}
+ /* now perform the actual multiplication keeping i as the sum of the
+ * two logarithms */
size *= blk_size;
- size += remainder / divisor[units];
- remainder %= divisor[units];
+ /* and logarithmically reduce it until it's just under the divisor */
while (size >= divisor[units]) {
remainder = do_div(size, divisor[units]);
i++;
}
+ /* work out in j how many digits of precision we need from the
+ * remainder */
sf_cap = size;
for (j = 0; sf_cap*10 < 1000; j++)
sf_cap *= 10;
- if (j) {
+ if (units == STRING_UNITS_2) {
+ /* express the remainder as a decimal. It's currently the
+ * numerator of a fraction whose denominator is
+ * divisor[units], which is 1 << 10 for STRING_UNITS_2 */
remainder *= 1000;
- remainder /= divisor[units];
+ remainder >>= 10;
+ }
+
+ /* add a 5 to the digit below what will be printed to ensure
+ * an arithmetical round up and carry it through to size */
+ remainder += rounding[j];
+ if (remainder >= 1000) {
+ remainder -= 1000;
+ size += 1;
+ }
+
+ if (j) {
snprintf(tmp, sizeof(tmp), ".%03u", remainder);
tmp[j+1] = '\0';
}
* @dst: destination buffer (escaped)
* @osz: destination buffer size
* @flags: combination of the flags (bitwise OR):
- * %ESCAPE_SPACE:
+ * %ESCAPE_SPACE: (special white space, not space itself)
* '\f' - form feed
* '\n' - new line
* '\r' - carriage return
* all previous together
* %ESCAPE_HEX:
* '\xHH' - byte with hexadecimal value HH (2 digits)
- * @esc: NULL-terminated string of characters any of which, if found in
- * the source, has to be escaped
+ * @only: NULL-terminated string containing characters used to limit
+ * the selected escape class. If characters are included in @only
+ * that would not normally be escaped by the classes selected
+ * in @flags, they will be copied to @dst unescaped.
*
* Description:
* The process of escaping byte buffer includes several parts. They are applied
* in the following sequence.
* 1. The character is matched to the printable class, if asked, and in
* case of match it passes through to the output.
- * 2. The character is not matched to the one from @esc string and thus
- * must go as is to the output.
+ * 2. The character is not matched to the one from @only string and thus
+ * must go as-is to the output.
* 3. The character is checked if it falls into the class given by @flags.
* %ESCAPE_OCTAL and %ESCAPE_HEX are going last since they cover any
* character. Note that they actually can't go together, otherwise
* dst for a '\0' terminator if and only if ret < osz.
*/
int string_escape_mem(const char *src, size_t isz, char *dst, size_t osz,
- unsigned int flags, const char *esc)
+ unsigned int flags, const char *only)
{
char *p = dst;
char *end = p + osz;
- bool is_dict = esc && *esc;
+ bool is_dict = only && *only;
while (isz--) {
unsigned char c = *src++;
* Apply rules in the following sequence:
* - the character is printable, when @flags has
* %ESCAPE_NP bit set
- * - the @esc string is supplied and does not contain a
+ * - the @only string is supplied and does not contain a
* character under question
* - the character doesn't fall into a class of symbols
* defined by given @flags
* output buffer.
*/
if ((flags & ESCAPE_NP && isprint(c)) ||
- (is_dict && !strchr(esc, c))) {
+ (is_dict && !strchr(only, c))) {
/* do nothing */
} else {
if (flags & ESCAPE_SPACE && escape_space(c, &p, end))
Code Review / kvmfornfv.git / blobdiff