From: WanBingjiang <wanbingjiang@webray.com.cn>
Date: Mon, 27 Apr 2026 06:51:25 +0000 (+0800)
Subject: bits: add --expand option to output individual bit IDs
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=8033c13501b504d938dad3ebc7fcaccb67c61d63;p=thirdparty%2Futil-linux.git

bits: add --expand option to output individual bit IDs

Add -e/--expand output mode that prints each set bit as a
comma-separated list without range compression. This is useful
for scripting when individual IDs are needed (e.g., CPU ID iteration).

Example: bits --expand 1,3-5,7 → 1,3,4,5,7
Signed-off-by: WanBingjiang <wanbingjiang@webray.com.cn>
---

diff --git a/include/cpuset.h b/include/cpuset.h
index 119c1a04c..dbdbe691e 100644
--- a/include/cpuset.h
+++ b/include/cpuset.h
@@ -93,6 +93,7 @@ extern cpu_set_t *cpuset_alloc(int ncpus, size_t *setsize, size_t *nbits);
 extern void cpuset_free(cpu_set_t *set);
 
 extern char *cpulist_create(char *str, size_t len, cpu_set_t *set, size_t setsize);
+extern char *cpulist_flat_create(char *str, size_t len, cpu_set_t *set, size_t setsize);
 extern int cpulist_parse(const char *str, cpu_set_t *set, size_t setsize, int fail);
 
 extern char *cpumask_create(char *str, size_t len, cpu_set_t *set, size_t setsize);
diff --git a/lib/cpuset.c b/lib/cpuset.c
index c5679888e..aba5d5056 100644
--- a/lib/cpuset.c
+++ b/lib/cpuset.c
@@ -220,6 +220,38 @@ char *cpulist_create(char *str, size_t len,
 	return str;
 }
 
+/*
+ * cpulist_flat_create - Convert cpumask to flat comma-separated list
+ * Output: ONLY single CPUs, NO ranges (e.g. "0,1,2,3,4")
+ */
+char *cpulist_flat_create(char *str, size_t len,
+			    cpu_set_t *set, size_t setsize)
+{
+	char *ptr = str;
+	int entry_made = 0;
+	size_t max = cpuset_nbits(setsize);
+	size_t cpu;
+	int rlen;
+
+	for (cpu = 0; cpu < max; cpu++) {
+		if (!CPU_ISSET_S(cpu, setsize, set))
+			continue;
+
+		rlen = snprintf(ptr, len, "%zu,", cpu);
+		if (rlen < 0 || (size_t)rlen >= len)
+			return NULL;
+
+		ptr += rlen;
+		len -= rlen;
+		entry_made = 1;
+	}
+	ptr -= entry_made;
+	*ptr = '\0';
+
+	return str;
+}
+
+
 /*
  * Returns string with CPU mask.
  */
diff --git a/text-utils/bits.1.adoc b/text-utils/bits.1.adoc
index 770ad363e..534bcf0e9 100644
--- a/text-utils/bits.1.adoc
+++ b/text-utils/bits.1.adoc
@@ -91,6 +91,9 @@ Print the combined arguments as a binary mask value.
 Print the combined arguments as a hexadecimal mask value
 in 32-bit comma-separated groups.
 
+*-e*, *--expand*::
+Print the combined arguments as a list of individual bit IDs.
+
 *-l*, *--list*::
 Print the combined arguments as a list of bit IDs.
 Consecutive IDs are compressed to ranges.
@@ -122,6 +125,9 @@ Print the combined arguments as a hexadecimal mask value (default).
 ~$ bits --grouped-mask 2,22,74,79
 8400,00000000,00400004
 
+~$ bits --expand 1,3-5,7
+1,3,4,5,7
+
 ~$ bits --width 64 --list 2,22,74,79
 2,22
 ....
diff --git a/text-utils/bits.c b/text-utils/bits.c
index dbeaa09b7..9b55583b3 100644
--- a/text-utils/bits.c
+++ b/text-utils/bits.c
@@ -110,6 +110,7 @@ static size_t num_digits(size_t value)
 
 enum output_mode {
 	MODE_BINARY,
+	MODE_EXPAND,
 	MODE_GROUPED_MASK,
 	MODE_LIST,
 	MODE_MASK,
@@ -134,6 +135,7 @@ static void print_bits(cpu_set_t *bits, size_t width, enum output_mode mode)
 		case MODE_BINARY:
 			printf("0b0\n");
 			break;
+		case MODE_EXPAND:
 		case MODE_LIST:
 			break;
 		}
@@ -189,13 +191,14 @@ static void print_bits(cpu_set_t *bits, size_t width, enum output_mode mode)
 		printf("\n");
 		break;
 
+	case MODE_EXPAND:
 	case MODE_LIST:
-		/* Maximum number of digits (larger bit number) plus 1
-		 * to account for a separating comma, times the number of bits
-		 * set to 1. */
 		buf_size = (num_digits(width - 1) + 1) * CPU_COUNT_S(size, bits);
 		buf = xmalloc(buf_size);
-		cpulist_create(buf, buf_size, bits, size);
+		if (mode == MODE_EXPAND)
+			cpulist_flat_create(buf, buf_size, bits, size);
+		else
+			cpulist_create(buf, buf_size, bits, size);
 		printf("%s\n", buf);
 		break;
 	}
@@ -233,6 +236,7 @@ static void __attribute__((__noreturn__)) usage(void)
 		  "                       comma separated groups"), stdout);
 	fputsln(_(" -b, --binary        display bits as a binary mask value"),
 		stdout);
+	fputsln(_(" -e, --expand        display bits as an expanded list of bit IDs"), stdout);
 	fputsln(_(" -l, --list          display bits as a compressed list of bit IDs"),
 		stdout);
 
@@ -249,7 +253,7 @@ int main(int argc, char **argv)
 	size_t alloc_size;
 	int c;
 
-#define FLAGS "Vhw:mgbl"
+#define FLAGS "Vhw:mgble"
 	static const struct option longopts[] = {
 		{ "version",      no_argument,       NULL, 'V' },
 		{ "help",         no_argument,       NULL, 'h' },
@@ -257,6 +261,7 @@ int main(int argc, char **argv)
 		{ "mask",         no_argument,       NULL, 'm' },
 		{ "grouped-mask", no_argument,       NULL, 'g' },
 		{ "binary",       no_argument,       NULL, 'b' },
+		{ "expand",       no_argument,       NULL, 'e' },
 		{ "list",         no_argument,       NULL, 'l' },
 		{ NULL,           0,                 NULL,  0  }
 	};
@@ -277,6 +282,9 @@ int main(int argc, char **argv)
 		case 'b':
 			mode = MODE_BINARY;
 			break;
+		case 'e':
+			mode = MODE_EXPAND;
+			break;
 		case 'l':
 			mode = MODE_LIST;
 			break;