libbb/human_readable.c: shrink; and reduce bss usage

also, move smart_ulltoaN there and comment usage locations

function                                             old     new   delta
static.unit_chars                                      7       9      +2
utoa_to_buf                                          110     108      -2
make_human_readable_str                              262     258      -4
fallbackSort                                        1723    1719      -4
static.fmt                                            97      92      -5
static.fmt_tenths                                     10       -     -10
static.str                                            21       4     -17
------------------------------------------------------------------------------
(add/remove: 0/1 grow/shrink: 1/5 up/down: 2/-42)             Total: -40 bytes
   text    data     bss     dec     hex filename
 820981     453    6932  828366   ca3ce busybox_old
 820968     453    6916  828337   ca3b1 busybox_unstripped

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 130 insertions, 32 deletions

diff --git a/libbb/human_readable.c b/libbb/human_readable.c
index 05e7d86ec..3050d7d1e 100644
--- a/libbb/human_readable.c
+++ b/libbb/human_readable.c
@@ -30,70 +30,168 @@
 
 #include "libbb.h"
 
-const char* FAST_FUNC make_human_readable_str(unsigned long long size,
+const char* FAST_FUNC make_human_readable_str(unsigned long long val,
 	unsigned long block_size, unsigned long display_unit)
 {
-	/* The code will adjust for additional (appended) units */
 	static const char unit_chars[] ALIGN1 = {
-		'\0', 'K', 'M', 'G', 'T', 'P', 'E'
+		'\0', 'K', 'M', 'G', 'T', 'P', 'E', 'Z', 'Y'
 	};
-	static const char fmt[] ALIGN1 = "%llu";
-	static const char fmt_tenths[] ALIGN1 = "%llu.%d%c";
 
-	static char str[21] ALIGN1;  /* Sufficient for 64 bit unsigned integers */
+	static char *str;
 
-	unsigned long long val;
-	int frac;
+	unsigned frac; /* 0..9 - the fractional digit */
 	const char *u;
-	const char *f;
-	smallint no_tenths;
+	const char *fmt;
 
-	if (size == 0)
+	if (val == 0)
 		return "0";
 
-	/* If block_size is 0 then do not print tenths */
-	no_tenths = 0;
-	if (block_size == 0) {
-		no_tenths = 1;
-		block_size = 1;
-	}
-
-	u = unit_chars;
-	val = size * block_size;
-	f = fmt;
+	fmt = "%llu";
+	if (block_size > 1)
+		val *= block_size;
 	frac = 0;
+	u = unit_chars;
 
 	if (display_unit) {
 		val += display_unit/2;	/* Deal with rounding */
-		val /= display_unit;	/* Don't combine with the line above!!! */
+		val /= display_unit;	/* Don't combine with the line above! */
 		/* will just print it as ulonglong (below) */
 	} else {
 		while ((val >= 1024)
-		 && (u < unit_chars + sizeof(unit_chars) - 1)
+		 /* && (u < unit_chars + sizeof(unit_chars) - 1) - never happens */
 		) {
-			f = fmt_tenths;
+			fmt = "%llu.%u%c";
 			u++;
-			frac = (((int)(val % 1024)) * 10 + 1024/2) / 1024;
+			frac = (((unsigned)val % 1024) * 10 + 1024/2) / 1024;
 			val /= 1024;
 		}
-		if (frac >= 10) {		/* We need to round up here. */
+		if (frac >= 10) { /* we need to round up here */
 			++val;
 			frac = 0;
 		}
 #if 1
-		/* Sample code to omit decimal point and tenths digit. */
-		if (no_tenths) {
+		/* If block_size is 0, dont print fractional part */
+		if (block_size == 0) {
 			if (frac >= 5) {
 				++val;
 			}
-			f = "%llu%*c" /* fmt_no_tenths */;
+			fmt = "%llu%*c";
 			frac = 1;
 		}
 #endif
 	}
 
-	/* If f==fmt then 'frac' and 'u' are ignored. */
-	snprintf(str, sizeof(str), f, val, frac, *u);
-
+	if (!str) {
+		/* sufficient for any width of val */
+		str = xmalloc(sizeof(val)*3 + 2 + 3);
+	}
+	sprintf(str, fmt, val, frac, *u);
 	return str;
 }
+
+
+/* vda's implementations of the similar idea */
+
+/* Convert unsigned long long value into compact 5-char representation.
+ * String is not terminated (buf[5] is untouched) */
+void FAST_FUNC smart_ulltoa5(unsigned long long ul, char buf[6], const char *scale)
+{
+	const char *fmt;
+	char c;
+	unsigned v, u, idx = 0;
+
+	if (ul > 99999) { // do not scale if 99999 or less
+		ul *= 10;
+		do {
+			ul /= 1024;
+			idx++;
+		} while (ul >= 100000);
+	}
+	v = ul; // ullong divisions are expensive, avoid them
+
+	fmt = " 123456789";
+	u = v / 10;
+	v = v % 10;
+	if (!idx) {
+		// 99999 or less: use "12345" format
+		// u is value/10, v is last digit
+		c = buf[0] = " 123456789"[u/1000];
+		if (c != ' ') fmt = "0123456789";
+		c = buf[1] = fmt[u/100%10];
+		if (c != ' ') fmt = "0123456789";
+		c = buf[2] = fmt[u/10%10];
+		if (c != ' ') fmt = "0123456789";
+		buf[3] = fmt[u%10];
+		buf[4] = "0123456789"[v];
+	} else {
+		// value has been scaled into 0..9999.9 range
+		// u is value, v is 1/10ths (allows for 92.1M format)
+		if (u >= 100) {
+			// value is >= 100: use "1234M', " 123M" formats
+			c = buf[0] = " 123456789"[u/1000];
+			if (c != ' ') fmt = "0123456789";
+			c = buf[1] = fmt[u/100%10];
+			if (c != ' ') fmt = "0123456789";
+			v = u % 10;
+			u = u / 10;
+			buf[2] = fmt[u%10];
+		} else {
+			// value is < 100: use "92.1M" format
+			c = buf[0] = " 123456789"[u/10];
+			if (c != ' ') fmt = "0123456789";
+			buf[1] = fmt[u%10];
+			buf[2] = '.';
+		}
+		buf[3] = "0123456789"[v];
+		buf[4] = scale[idx]; /* typically scale = " kmgt..." */
+	}
+}
+
+/* Convert unsigned long long value into compact 4-char
+ * representation. Examples: "1234", "1.2k", " 27M", "123T"
+ * String is not terminated (buf[4] is untouched) */
+void FAST_FUNC smart_ulltoa4(unsigned long long ul, char buf[5], const char *scale)
+{
+	const char *fmt;
+	char c;
+	unsigned v, u, idx = 0;
+
+	if (ul > 9999) { // do not scale if 9999 or less
+		ul *= 10;
+		do {
+			ul /= 1024;
+			idx++;
+		} while (ul >= 10000);
+	}
+	v = ul; // ullong divisions are expensive, avoid them
+
+	fmt = " 123456789";
+	u = v / 10;
+	v = v % 10;
+	if (!idx) {
+		// 9999 or less: use "1234" format
+		// u is value/10, v is last digit
+		c = buf[0] = " 123456789"[u/100];
+		if (c != ' ') fmt = "0123456789";
+		c = buf[1] = fmt[u/10%10];
+		if (c != ' ') fmt = "0123456789";
+		buf[2] = fmt[u%10];
+		buf[3] = "0123456789"[v];
+	} else {
+		// u is value, v is 1/10ths (allows for 9.2M format)
+		if (u >= 10) {
+			// value is >= 10: use "123M', " 12M" formats
+			c = buf[0] = " 123456789"[u/100];
+			if (c != ' ') fmt = "0123456789";
+			v = u % 10;
+			u = u / 10;
+			buf[1] = fmt[u%10];
+		} else {
+			// value is < 10: use "9.2M" format
+			buf[0] = "0123456789"[u];
+			buf[1] = '.';
+		}
+		buf[2] = "0123456789"[v];
+		buf[3] = scale[idx]; /* typically scale = " kmgt..." */
+	}
+}