From c896d07fec6d949328a4ef09a80c47fe6f682e67 Mon Sep 17 00:00:00 2001 From: 0xf00sec <159052166+0xf00sec@users.noreply.github.com> Date: Sun, 10 Aug 2025 15:41:43 +0300 Subject: feat(libSystem): implement memory ops with alignment & overlap handling --- dev/libSystem/src/SystemCalls.cc | 167 +++++++++++++++++++++------------------ 1 file changed, 92 insertions(+), 75 deletions(-) (limited to 'dev/libSystem/src') diff --git a/dev/libSystem/src/SystemCalls.cc b/dev/libSystem/src/SystemCalls.cc index 71eebc62..83569b6f 100644 --- a/dev/libSystem/src/SystemCalls.cc +++ b/dev/libSystem/src/SystemCalls.cc @@ -7,9 +7,6 @@ #include #include -/// @file SystemAPI.cc -/// @brief System wide API for NeKernel. - namespace Detail { template inline VoidPtr safe_void_cast(const T* ptr) { @@ -17,33 +14,67 @@ namespace Detail { } } +// memmove-style copy IMPORT_C VoidPtr MmCopyMemory(_Input VoidPtr dest, _Input VoidPtr src, _Input SizeT len) { - if (!len || !dest || !src) { - return nullptr; - } - - auto src_bytes = static_cast(src); - auto dst_bytes = static_cast(dest); - - if (len >= sizeof(UInt64) && - (reinterpret_cast(src) % sizeof(UInt64)) == 0 && - (reinterpret_cast(dest) % sizeof(UInt64)) == 0) { - - auto src_words = static_cast(src); - auto dst_words = static_cast(dest); - SizeT word_count = len / sizeof(UInt64); - - for (SizeT i = 0; i < word_count; ++i) { - dst_words[i] = src_words[i]; - } - - SizeT remaining = len % sizeof(UInt64); - for (SizeT i = 0; i < remaining; ++i) { - dst_bytes[len - remaining + i] = src_bytes[len - remaining + i]; + // handles overlap, prefers 64-bit word copies when aligned + if (!len || !dest || !src) return nullptr; + + auto s = static_cast(src); + auto d = static_cast(dest); + + if (d == s) return dest; + + // decide direction + if (d > s && d < s + len) { + const UInt8* rs = s + len; + UInt8* rd = d + len; + + // try 64-bit aligned backward copy + if (len >= sizeof(UInt64) && + (reinterpret_cast(rs) % sizeof(UInt64) == 0) && + (reinterpret_cast(rd) % sizeof(UInt64) == 0)) { + + auto rsw = reinterpret_cast(rs); + auto rdw = reinterpret_cast(rd); + SizeT words = len / sizeof(UInt64); + + for (SizeT i = 0; i < words; ++i) { + rdw[-1 - static_cast(i)] = rsw[-1 - static_cast(i)]; + } + + SizeT rem = len % sizeof(UInt64); + for (SizeT i = 0; i < rem; ++i) { + rd[-1 - i] = rs[-1 - i]; + } + } else { + // byte-wise backward + for (SizeT i = 0; i < len; ++i) { + rd[-1 - i] = rs[-1 - i]; + } } } else { - for (SizeT i = 0; i < len; ++i) { - dst_bytes[i] = src_bytes[i]; + // try 64-bit aligned forward copy + if (len >= sizeof(UInt64) && + (reinterpret_cast(s) % sizeof(UInt64) == 0) && + (reinterpret_cast(d) % sizeof(UInt64) == 0)) { + + auto sw = reinterpret_cast(s); + auto dw = reinterpret_cast(d); + SizeT words = len / sizeof(UInt64); + + for (SizeT i = 0; i < words; ++i) { + dw[i] = sw[i]; + } + + SizeT rem = len % sizeof(UInt64); + const SizeT offset = words * sizeof(UInt64); + for (SizeT i = 0; i < rem; ++i) { + d[offset + i] = s[offset + i]; + } + } else { + for (SizeT i = 0; i < len; ++i) { + d[i] = s[i]; + } } } @@ -51,46 +82,38 @@ IMPORT_C VoidPtr MmCopyMemory(_Input VoidPtr dest, _Input VoidPtr src, _Input Si } IMPORT_C SInt64 MmStrLen(const Char* in) { + // strlen via pointer walk if (!in) return 0; - - SizeT len = 0; - - while (in[len] != '\0') { - ++len; - } - - return static_cast(len); + const Char* p = in; + while (*p) ++p; + return static_cast(p - in); } IMPORT_C VoidPtr MmFillMemory(_Input VoidPtr dest, _Input SizeT len, _Input UInt8 value) { - if (!len || !dest) { - return nullptr; - } + if (!len || !dest) return nullptr; + + auto d = static_cast(dest); - auto dst_bytes = static_cast(dest); - - if (len >= sizeof(UInt64) && (reinterpret_cast(dest) % sizeof(UInt64)) == 0) { - // 64-bit pattern + if (len >= sizeof(UInt64) && (reinterpret_cast(d) % sizeof(UInt64)) == 0) { UInt64 pattern = static_cast(value); pattern |= (pattern << 8); pattern |= (pattern << 16); pattern |= (pattern << 32); - - auto dst_words = static_cast(dest); - SizeT word_count = len / sizeof(UInt64); - - for (SizeT i = 0; i < word_count; ++i) { - dst_words[i] = pattern; + + auto dw = reinterpret_cast(d); + SizeT words = len / sizeof(UInt64); + + for (SizeT i = 0; i < words; ++i) { + dw[i] = pattern; } - - SizeT remaining = len % sizeof(UInt64); - for (SizeT i = 0; i < remaining; ++i) { - dst_bytes[len - remaining + i] = value; + + SizeT rem = len % sizeof(UInt64); + const SizeT offset = words * sizeof(UInt64); + for (SizeT i = 0; i < rem; ++i) { + d[offset + i] = value; } } else { - for (SizeT i = 0; i < len; ++i) { - dst_bytes[i] = value; - } + for (SizeT i = 0; i < len; ++i) d[i] = value; } return dest; @@ -109,13 +132,11 @@ IMPORT_C Void IoCloseFile(_Input Ref desc) { IMPORT_C UInt64 IoSeekFile(_Input Ref desc, _Input UInt64 off) { auto ret_ptr = libsys_syscall_arg_3( - SYSCALL_HASH("IoSeekFile"), - static_cast(desc), + SYSCALL_HASH("IoSeekFile"), + static_cast(desc), reinterpret_cast(&off)); - if (!ret_ptr) { - return ~0UL; - } + if (!ret_ptr) return ~0UL; auto ret = static_cast(ret_ptr); UInt64 result = *ret; @@ -126,31 +147,27 @@ IMPORT_C UInt64 IoSeekFile(_Input Ref desc, _Input UInt64 off) { IMPORT_C UInt64 IoTellFile(_Input Ref desc) { auto ret_ptr = libsys_syscall_arg_2(SYSCALL_HASH("IoTellFile"), static_cast(desc)); - - if (!ret_ptr) { - return ~0UL; - } - + if (!ret_ptr) return ~0UL; auto ret = static_cast(ret_ptr); return *ret; } IMPORT_C SInt32 PrintOut(_Input IORef desc, const char* fmt, ...) { + constexpr SizeT BUF_SZ = 1024; + char buf[BUF_SZ]; + va_list args; va_start(args, fmt); + int needed = vsnprintf(buf, BUF_SZ, fmt, args); + va_end(args); - auto ret_ptr = libsys_syscall_arg_4( - SYSCALL_HASH("PrintOut"), + // if truncated, `needed` >= BUF_SZ; we still send truncated buffer + auto ret_ptr = libsys_syscall_arg_3( + SYSCALL_HASH("PrintOut"), static_cast(desc), - Detail::safe_void_cast(fmt), - static_cast(&args)); + Detail::safe_void_cast(buf)); - va_end(args); - - if (!ret_ptr) { - return -1; - } - + if (!ret_ptr) return -1; auto ret = static_cast(ret_ptr); return *ret; } -- cgit v1.2.3