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Subject[PATCH v4 11/34] vsprintf: Improve number()
Date
This patch refactors number() to make it a bit clearer, and it also
changes it to call printbuf_make_room() only once at the start, instead
of in the printbuf output helpers.

Signed-off-by: Kent Overstreet <kent.overstreet@gmail.com>
---
lib/vsprintf.c | 83 +++++++++++++++++++++++++-------------------------
1 file changed, 41 insertions(+), 42 deletions(-)

diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 5afa74dda5..7d20406deb 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -458,93 +458,92 @@ void number(struct printbuf *out, unsigned long long num,
{
/* put_dec requires 2-byte alignment of the buffer. */
char tmp[3 * sizeof(num)] __aligned(2);
- char sign;
- char locase;
+ char sign = 0;
+ /* locase = 0 or 0x20. ORing digits or letters with 'locase'
+ * produces same digits or (maybe lowercased) letters */
+ char locase = (spec.flags & SMALL);
int need_pfx = ((spec.flags & SPECIAL) && spec.base != 10);
- int i;
bool is_zero = num == 0LL;
int field_width = spec.field_width;
int precision = spec.precision;
+ int nr_digits = 0;
+ int output_bytes = 0;

- /* locase = 0 or 0x20. ORing digits or letters with 'locase'
- * produces same digits or (maybe lowercased) letters */
- locase = (spec.flags & SMALL);
if (spec.flags & LEFT)
spec.flags &= ~ZEROPAD;
- sign = 0;
if (spec.flags & SIGN) {
if ((signed long long)num < 0) {
sign = '-';
num = -(signed long long)num;
- field_width--;
+ output_bytes++;
} else if (spec.flags & PLUS) {
sign = '+';
- field_width--;
+ output_bytes++;
} else if (spec.flags & SPACE) {
sign = ' ';
- field_width--;
+ output_bytes++;
}
}
if (need_pfx) {
if (spec.base == 16)
- field_width -= 2;
+ output_bytes += 2;
else if (!is_zero)
- field_width--;
+ output_bytes++;
}

/* generate full string in tmp[], in reverse order */
- i = 0;
- if (num < spec.base)
- tmp[i++] = hex_asc_upper[num] | locase;
- else if (spec.base != 10) { /* 8 or 16 */
+ if (spec.base == 10) {
+ nr_digits = put_dec(tmp, num) - tmp;
+ } else { /* 8 or 16 */
int mask = spec.base - 1;
- int shift = 3;
+ int shift = ilog2((unsigned) spec.base);

- if (spec.base == 16)
- shift = 4;
do {
- tmp[i++] = (hex_asc_upper[((unsigned char)num) & mask] | locase);
+ tmp[nr_digits++] = (hex_asc_upper[((unsigned char)num) & mask] | locase);
num >>= shift;
} while (num);
- } else { /* base 10 */
- i = put_dec(tmp, num) - tmp;
}

/* printing 100 using %2d gives "100", not "00" */
- if (i > precision)
- precision = i;
+ precision = max(nr_digits, precision);
+ output_bytes += precision;
+ field_width = max(0, field_width - output_bytes);
+
+ printbuf_make_room(out, field_width + output_bytes);
+
/* leading space padding */
- field_width = max(0, field_width - precision);
if (!(spec.flags & (ZEROPAD | LEFT)) && field_width) {
- __prt_chars(out, ' ', field_width);
+ __prt_chars_reserved(out, ' ', field_width);
field_width = 0;
}
+
/* sign */
if (sign)
- __prt_char(out, sign);
+ __prt_char_reserved(out, sign);
+
/* "0x" / "0" prefix */
if (need_pfx) {
if (spec.base == 16 || !is_zero)
- __prt_char(out, '0');
+ __prt_char_reserved(out, '0');
if (spec.base == 16)
- __prt_char(out, 'X' | locase);
+ __prt_char_reserved(out, 'X' | locase);
}
- /* zero or space padding */
- if (!(spec.flags & LEFT) && field_width) {
- char c = ' ' + (spec.flags & ZEROPAD);

- __prt_chars(out, c, field_width);
- field_width = 0;
- }
- /* hmm even more zero padding? */
- if (precision > i)
- __prt_chars(out, '0', precision - i);
+ /* zero padding */
+ if (!(spec.flags & LEFT) && field_width)
+ __prt_chars_reserved(out, '0', field_width);
+
+ /* zero padding from precision */
+ if (precision > nr_digits)
+ __prt_chars_reserved(out, '0', precision - nr_digits);
+
/* actual digits of result */
- while (--i >= 0)
- __prt_char(out, tmp[i]);
+ while (--nr_digits >= 0)
+ __prt_char_reserved(out, tmp[nr_digits]);
+
/* trailing space padding */
- if (field_width)
- __prt_chars(out, ' ', field_width);
+ if ((spec.flags & LEFT) && field_width)
+ __prt_chars_reserved(out, ' ', field_width);

printbuf_nul_terminate(out);
}
--
2.36.1
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