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/*
* Copyright © 2023 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. */
static inline u32 mem_load32(const void *p) {
// XXX: Turns out the pedantically-safe approach below causes most compilers
// to generate horribly braindead x86 output in at least some cases (and the
// cases also differ by compiler). So, for now, use the simple pointer cast
// instead, even though it's technically UB - it'll be fine probably...
return *(u32 *)p;
// For future reference, the pedantically-safe approach would be to do this:
//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. */
static inline u64 mem_load64(const void *p) {
// this seems not to get butchered as badly in most cases?
return (u64)mem_load32(p) | (u64)mem_load32((uchar *)p + 4) << 32;
}
/* Retrieves a pointer from an unaligned pointer-to-pointer. */
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. */
static inline ssize mem_loadoffset(const void *p) {
return (ssize)mem_loadptr(p);
}
/* Adds a byte count to a pointer and returns a freely-assignable pointer. */
static inline void *mem_offset(void *p, int off) { return (char *)p + off; }
/* Returns the offset in bytes from one pointer to another (p - q). */
static inline ssize mem_diff(const void *p, const void *q) {
return (char *)p - (char *)q;
}
#endif
// vi: sw=4 ts=4 noet tw=80 cc=80
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