diff options
Diffstat (limited to 'src/mem.h')
| -rw-r--r-- | src/mem.h | 44 |
1 files changed, 15 insertions, 29 deletions
@@ -1,5 +1,5 @@ /* - * Copyright © 2021 Michael Smith <mikesmiffy128@gmail.com> + * 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 @@ -19,18 +19,25 @@ #include "intdefs.h" -/* retrieves a 32-bit integer from an unaligned pointer; avoids UB, probably */ +/* retrieves a 32-bit integer from an unaligned pointer */ 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; + // 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; avoids UB, possibly */ +/* 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; avoids UB, maybe */ +/* 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); @@ -39,33 +46,12 @@ static inline void *mem_loadptr(const void *p) { #endif } -/* retreives a signed offset from an unaligned pointer; avoids UB, hopefully */ +/* retreives a signed offset from an unaligned pointer */ 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 */ +/* adds a byte count to a pointer and returns a freely-assignable void 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) */ |