Factor out libmisc/endian.h

1 files changed, 129 insertions, 0 deletions

diff --git a/libmisc/include/libmisc/endian.h b/libmisc/include/libmisc/endian.h
new file mode 100644
index 0000000..eaf9bae
--- /dev/null
+++ b/libmisc/include/libmisc/endian.h
@@ -0,0 +1,129 @@
+/* libmisc/endian.h - Endian-conversion helpers
+ *
+ * Copyright (C) 2024  Luke T. Shumaker <lukeshu@lukeshu.com>
+ * SPDX-Licence-Identifier: AGPL-3.0-or-later
+ */
+
+#ifndef _LIBMISC_ENDIAN_H_
+#define _LIBMISC_ENDIAN_H_
+
+#include <assert.h>
+#include <stdint.h> /* for uint{n}_t */
+
+/* Big endian *****************************************************************/
+
+typedef struct {
+	uint8_t octets[2];
+} uint16be_t;
+static_assert(sizeof(uint16be_t) == 2);
+
+static inline void uint16be_encode(uint8_t *out, uint16_t in) {
+	out[0] = (uint8_t)((in >> 8) & 0xFF);
+	out[1] = (uint8_t)((in >> 0) & 0xFF);
+}
+
+static inline uint16_t uint16be_decode(uint8_t *in) {
+	return (((uint16_t)(in[0])) << 8)
+	     | (((uint16_t)(in[1])) << 0)
+	     ;
+}
+
+static inline uint16be_t uint16be_marshal(uint16_t in) {
+	uint16be_t out;
+	uint16be_encode(out.octets, in);
+	return out;
+}
+
+static inline uint16_t uint16be_unmarshal(uint16be_t in) {
+	return uint16be_decode(in.octets);
+}
+
+typedef struct {
+	uint8_t octets[4];
+} uint32be_t;
+static_assert(sizeof(uint32be_t) == 4);
+
+static inline void uint32be_encode(uint8_t *out, uint32_t in) {
+	out[0] = (uint8_t)((in >> 24) & 0xFF);
+	out[1] = (uint8_t)((in >> 16) & 0xFF);
+	out[2] = (uint8_t)((in >>  8) & 0xFF);
+	out[3] = (uint8_t)((in >>  0) & 0xFF);
+}
+
+static inline uint32_t uint32be_decode(uint8_t *in) {
+	return (((uint32_t)(in[0])) << 24)
+	     | (((uint32_t)(in[1])) << 16)
+	     | (((uint32_t)(in[2])) <<  8)
+	     | (((uint32_t)(in[3])) <<  0)
+	     ;
+}
+
+static inline uint32be_t uint32be_marshal(uint32_t in) {
+	uint32be_t out;
+	uint32be_encode(out.octets, in);
+	return out;
+}
+
+static inline uint32_t uint32be_unmarshal(uint32be_t in) {
+	return uint32be_decode(in.octets);
+}
+
+/* Little endian **************************************************************/
+
+typedef struct {
+	uint8_t octets[2];
+} uint16le_t;
+static_assert(sizeof(uint16le_t) == 2);
+
+static inline void uint16le_encode(uint8_t *out, uint16_t in) {
+	out[0] = (uint8_t)((in >> 0) & 0xFF);
+	out[1] = (uint8_t)((in >> 8) & 0xFF);
+}
+
+static inline uint16_t uint16le_decode(uint8_t *in) {
+	return (((uint16_t)(in[0])) << 0)
+	     | (((uint16_t)(in[1])) << 8)
+	     ;
+}
+
+static inline uint16le_t uint16le_marshal(uint16_t in) {
+	uint16le_t out;
+	uint16le_encode(out.octets, in);
+	return out;
+}
+
+static inline uint16_t uint16le_unmarshal(uint16le_t in) {
+	return uint16le_decode(in.octets);
+}
+
+typedef struct {
+	uint8_t octets[4];
+} uint32le_t;
+static_assert(sizeof(uint32le_t) == 4);
+
+static inline void uint32le_encode(uint8_t *out, uint32_t in) {
+	out[0] = (uint8_t)((in >>  0) & 0xFF);
+	out[1] = (uint8_t)((in >>  8) & 0xFF);
+	out[2] = (uint8_t)((in >> 16) & 0xFF);
+	out[3] = (uint8_t)((in >> 24) & 0xFF);
+}
+
+static inline uint32_t uint32le_decode(uint8_t *in) {
+	return (((uint32_t)(in[0])) <<  0)
+	     | (((uint32_t)(in[1])) <<  8)
+	     | (((uint32_t)(in[2])) << 16)
+	     | (((uint32_t)(in[3])) << 24)
+	     ;
+}
+
+static inline uint32le_t uint32le_marshal(uint32_t in) {
+	uint32le_t out;
+	uint32le_encode(out.octets, in);
+	return out;
+}
+
+static inline uint32_t uint32le_unmarshal(uint32le_t in) {
+	return uint32le_decode(in.octets);
+}
+
+#endif /* _LIBMISC_ENDIAN_H_ */