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From: Kent Overstreet <kent.overstreet@linux.dev>
To: akpm@linux-foundation.org
Cc: linux-kernel@vger.kernel.org,
	Kent Overstreet <kent.overstreet@gmail.com>,
	Petr Mladek <pmladek@suse.com>,
	Rasmus Villemoes <linux@rasmusvillemoes.dk>
Subject: [PATCH 09/32] vsprintf: Improve number()
Date: Sun, 14 Aug 2022 17:19:48 -0400	[thread overview]
Message-ID: <20220814212011.1727798-10-kent.overstreet@linux.dev> (raw)
In-Reply-To: <20220814212011.1727798-1-kent.overstreet@linux.dev>

From: Kent Overstreet <kent.overstreet@gmail.com>

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>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
---
 lib/vsprintf.c | 83 +++++++++++++++++++++++++-------------------------
 1 file changed, 41 insertions(+), 42 deletions(-)

diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index 52dac8519a..87adc528c6 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -457,93 +457,92 @@ 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


  parent reply	other threads:[~2022-08-14 21:21 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-08-14 21:19 Printbufs v6 Kent Overstreet
2022-08-14 21:19 ` [PATCH 01/32] lib/printbuf: New data structure for printing strings Kent Overstreet
2022-08-14 21:19 ` [PATCH 02/32] lib/string_helpers: Convert string_escape_mem() to printbuf Kent Overstreet
2022-08-14 21:19 ` [PATCH 03/32] vsprintf: Convert " Kent Overstreet
2022-08-14 21:19 ` [PATCH 04/32] lib/hexdump: " Kent Overstreet
2022-08-14 21:19 ` [PATCH 05/32] lib/string_helpers: string_get_size() now returns characters wrote Kent Overstreet
2022-08-14 21:19 ` [PATCH 06/32] lib/printbuf: Heap allocation Kent Overstreet
2022-08-14 21:19 ` [PATCH 07/32] lib/printbuf: Tabstops, indenting Kent Overstreet
2022-08-14 21:19 ` [PATCH 08/32] lib/printbuf: Unit specifiers Kent Overstreet
2022-08-14 21:19 ` Kent Overstreet [this message]
2022-08-14 21:19 ` [PATCH 10/32] vsprintf: prt_u64_minwidth(), prt_u64() Kent Overstreet
2022-08-14 21:19 ` [PATCH 11/32] test_printf: Drop requirement that sprintf not write past nul Kent Overstreet
2022-08-14 21:19 ` [PATCH 12/32] vsprintf: Start consolidating printf_spec handling Kent Overstreet
2022-08-14 21:19 ` [PATCH 13/32] vsprintf: Refactor resource_string() Kent Overstreet
2022-08-14 21:19 ` [PATCH 14/32] vsprintf: Refactor fourcc_string() Kent Overstreet
2022-08-14 21:19 ` [PATCH 15/32] vsprintf: Refactor ip_addr_string() Kent Overstreet
2022-08-14 21:19 ` [PATCH 16/32] vsprintf: Refactor mac_address_string() Kent Overstreet
2022-08-14 21:19 ` [PATCH 17/32] vsprintf: time_and_date() no longer takes printf_spec Kent Overstreet
2022-08-14 21:19 ` [PATCH 18/32] vsprintf: flags_string() " Kent Overstreet
2022-08-14 21:19 ` [PATCH 19/32] vsprintf: Refactor device_node_string, fwnode_string Kent Overstreet
2022-08-14 21:19 ` [PATCH 20/32] vsprintf: Refactor hex_string, bitmap_string_list, bitmap_string Kent Overstreet
2022-08-14 21:20 ` [PATCH 21/32] Input/joystick/analog: Convert from seq_buf -> printbuf Kent Overstreet

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