Initial public snapshot

With code from Bill. Thanks Bill!

1 files changed, 73 insertions, 0 deletions

diff --git a/src/mem.h b/src/mem.h
new file mode 100644
index 0000000..2a3573d
--- /dev/null
+++ b/src/mem.h
@@ -0,0 +1,73 @@
+/*
+ * Copyright © 2021 Michael Smith <mikesmiffy128@gmail.com>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+ * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+ * AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+ * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+ * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+ * OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+ * PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#ifndef INC_MEMUTIL_H
+#define INC_MEMUTIL_H
+
+#include "intdefs.h"
+
+/* retrieves a 32-bit integer from an unaligned pointer; avoids UB, probably */
+static inline u32 mem_load32(const void *p) {
+	const uchar *cp = p;
+	return (u32)cp[0] | (u32)cp[1] << 8 | (u32)cp[2] << 16 | (u32)cp[3] << 24;
+}
+
+/* retrieves a 64-bit integer from an unaligned pointer; avoids UB, possibly */
+static inline u64 mem_load64(const void *p) {
+	return (u64)mem_load32(p) | (u64)mem_load32((uchar *)p + 4) << 32;
+}
+
+/* retrieves a pointer from an unaligned pointer-to-pointer; avoids UB, maybe */
+static inline void *mem_loadptr(const void *p) {
+#if defined(_WIN64) || defined(__x86_64__)
+	return (void *)mem_load64(p);
+#else
+	return (void *)mem_load32(p);
+#endif
+}
+
+/* retreives a signed offset from an unaligned pointer; avoids UB, hopefully */
+static inline ssize mem_loadoffset(const void *p) {
+	return (ssize)mem_loadptr(p);
+}
+
+/* stores a 32-bit integer to an unaligned pointer; avoids UB, most likely */
+static inline void mem_store32(void *p, u32 val) {
+	uchar *cp = p;
+	cp[0] = val; cp[1] = val >> 8; cp[2] = val >> 16; cp[3] = val >> 24;
+}
+
+/* stores a 64-bit integer to an unaligned pointer; avoids UB, I'd assume */
+static inline void mem_store64(void *p, u64 val) {
+	mem_store32(p, val); mem_store32((uchar *)p + 4, val >> 32);
+}
+
+/* stores a pointer value to an unaligned pointer; avoids UB, I guess */
+static inline void mem_storeptr(void *to, const void *val) {
+#if defined(_WIN64) || defined(__x86_64__)
+	mem_store64(to, (u64)val);
+#else
+	mem_store32(to, (u32)val);
+#endif
+}
+
+/* adds a byte count to a pointer, and returns something that can be assigned
+ * to any pointer type */
+static inline void *mem_offset(void *p, int off) { return (char *)p + off; }
+
+#endif
+
+// vi: sw=4 ts=4 noet tw=80 cc=80