Add get_byte and get_nibble to 8byte function set.

4 files changed, 42 insertions, 9 deletions

diff --git a/src/bitfield/8byte.c b/src/bitfield/8byte.c
index 845be8c0..f08f227d 100644
--- a/src/bitfield/8byte.c
+++ b/src/bitfield/8byte.c
@@ -18,8 +18,21 @@ static uint16_t bits_to_bytes(uint32_t bits) {
     return byte_count;
 }
 
+uint8_t eightbyte_get_nibble(const uint64_t source, const uint8_t nibble_index,
+        const bool big_endian) {
+    return get_bit_field(source, NIBBLE_SIZE * nibble_index, NIBBLE_SIZE,
+            big_endian);
+}
+
+uint8_t eightbyte_get_byte(const uint64_t source, const uint8_t byte_index,
+        const bool big_endian) {
+    // TODO we're not handling swapped endianness - we could use get_bit_field
+    // but this might be more efficient
+    return (source >> (EIGHTBYTE_BIT - ((byte_index + 1) * CHAR_BIT))) & 0xFF;
+}
+
 uint64_t get_bit_field(uint64_t source, const uint16_t offset,
-        const uint16_t bit_count, bool big_endian) {
+        const uint16_t bit_count, const bool big_endian) {
     int startByte = offset / CHAR_BIT;
     int endByte = (offset + bit_count - 1) / CHAR_BIT;
 
@@ -54,8 +67,3 @@ bool set_bit_field(uint64_t* destination, uint64_t value, const uint16_t offset,
     *destination |= value;
     return true;
 }
-
-uint8_t nth_byte(const uint64_t source, const uint16_t byte_index) {
-    return (source >> (EIGHTBYTE_BIT - ((byte_index + 1) * CHAR_BIT))) & 0xFF;
-}
-
diff --git a/src/bitfield/8byte.h b/src/bitfield/8byte.h
index 1ee9c0ec..818372d5 100644
--- a/src/bitfield/8byte.h
+++ b/src/bitfield/8byte.h
@@ -47,7 +47,32 @@ extern "C" {
  * Returns the value of the requested bit field, right aligned in a uint64_t.
  */
 uint64_t get_bit_field(uint64_t source, const uint16_t offset,
-        const uint16_t bit_count, bool big_endian);
+        const uint16_t bit_count, const bool big_endian);
+
+/* Public: Return a single nibble from the payload, with range checking.
+ *
+ * source - the source payload.
+ * nibble_index - the index of the nibble to retreive. The leftmost nibble is
+ *      index 0.
+ * big_endian - if the data passed in is little endian, set this to false and it
+ *      will be flipped before grabbing the bit field.
+ *
+ * Returns the retreived nibble, right aligned in a uint8_t.
+ */
+uint8_t eightbyte_get_nibble(const uint64_t source, const uint8_t nibble_index,
+                const bool big_endian);
+
+/* Public: Return a single byte from the payload, with range checking.
+ *
+ * source - the source byte array.
+ * byte_index - the index of the byte to retreive. The leftmost byte is index 0.
+ * big_endian - if the data passed in is little endian, set this to false and it
+ *      will be flipped before grabbing the bit field.
+ *
+ * Returns the retreived byte.
+ */
+uint8_t eightbyte_get_byte(const uint64_t source, const uint8_t byte_index,
+                const bool big_endian);
 
 /* Public: Set the bit field in the given data array to the new value.
  *
diff --git a/src/bitfield/bitfield.c b/src/bitfield/bitfield.c
index 7dfa7cd4..af17d485 100644
--- a/src/bitfield/bitfield.c
+++ b/src/bitfield/bitfield.c
@@ -3,8 +3,6 @@
 #include <string.h>
 #include <stddef.h>
 
-#define NIBBLE_SIZE (CHAR_BIT / 2)
-
 uint8_t get_nibble(const uint8_t source[], const uint8_t source_length,
                 const uint8_t nibble_index) {
     uint8_t byte_index = nibble_index / 2;
diff --git a/src/bitfield/bitfield.h b/src/bitfield/bitfield.h
index 52ed143d..b58e4e59 100644
--- a/src/bitfield/bitfield.h
+++ b/src/bitfield/bitfield.h
@@ -4,6 +4,8 @@
 #include <stdint.h>
 #include <stdbool.h>
 
+#define NIBBLE_SIZE (CHAR_BIT / 2)
+
 #ifdef __cplusplus
 extern "C" {
 #endif