optcmd: Add parser for 8-bit power of 2 integers

Signed-off-by: Alistair Popple <alistair@popple.id.au>

2 files changed, 27 insertions, 0 deletions

diff --git a/src/parsers.c b/src/parsers.c
index 868c383..8575784 100644
--- a/src/parsers.c
+++ b/src/parsers.c
@@ -1,3 +1,4 @@
+#include <stdio.h>
 #include <stdlib.h>
 #include <stdint.h>
 #include <stdbool.h>
@@ -55,6 +56,31 @@ uint16_t *parse_number16(const char *argv)
 	return n;
 }
 
+/* Parse an 8-bit number that is a power of 2 */
+uint8_t *parse_number8_pow2(const char *argv)
+{
+	uint8_t *n;
+	unsigned long int tmp, i;
+	char *endptr;
+
+	if (!argv)
+		return NULL;
+
+	errno = 0;
+	tmp = strtoul(argv, &endptr, 0);
+	if (tmp >= 256)
+		return NULL;
+
+	for (i = tmp; i; i >>= 1)
+		if ((i & 1) && (i >> 1))
+			return NULL;
+
+	n = malloc(sizeof(*n));
+	*n = tmp;
+
+	return n;
+}
+
 /* Parse a GPR number, returning an error if it's greater than 32 */
 int *parse_gpr(const char *argv)
 {
diff --git a/src/parsers.h b/src/parsers.h
index 935c242..ba52178 100644
--- a/src/parsers.h
+++ b/src/parsers.h
@@ -16,6 +16,7 @@
 uint64_t *parse_number64(const char *argv);
 uint32_t *parse_number32(const char *argv);
 uint16_t *parse_number16(const char *argv);
+uint8_t *parse_number8_pow2(const char *argv);
 int *parse_gpr(const char *argv);
 int *parse_spr(const char *argv);
 bool *parse_flag_noarg(const char *argv);