1 files changed, 97 insertions, 0 deletions
diff --git a/src/VBox/Runtime/common/string/memrchr.asm b/src/VBox/Runtime/common/string/memrchr.asm
new file mode 100644
index 00000000..068e7183
--- /dev/null
+++ b/src/VBox/Runtime/common/string/memrchr.asm
@@ -0,0 +1,97 @@
+; $Id: memrchr.asm $
+;; @file
+; IPRT - No-CRT memrchr - AMD64 & X86.
+;
+
+;
+; Copyright (C) 2006-2020 Oracle Corporation
+;
+; This file is part of VirtualBox Open Source Edition (OSE), as
+; available from http://www.virtualbox.org. This file is free software;
+; you can redistribute it and/or modify it under the terms of the GNU
+; General Public License (GPL) as published by the Free Software
+; Foundation, in version 2 as it comes in the "COPYING" file of the
+; VirtualBox OSE distribution. VirtualBox OSE is distributed in the
+; hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
+;
+; The contents of this file may alternatively be used under the terms
+; of the Common Development and Distribution License Version 1.0
+; (CDDL) only, as it comes in the "COPYING.CDDL" file of the
+; VirtualBox OSE distribution, in which case the provisions of the
+; CDDL are applicable instead of those of the GPL.
+;
+; You may elect to license modified versions of this file under the
+; terms and conditions of either the GPL or the CDDL or both.
+;
+
+%include "iprt/asmdefs.mac"
+
+BEGINCODE
+
+;;
+; @param    pv      gcc: rdi  msc: ecx  x86:[esp+4]   wcall: eax
+; @param    ch      gcc: esi  msc: edx  x86:[esp+8]   wcall: edx
+; @param    cb      gcc: rdx  msc: r8   x86:[esp+0ch] wcall: ebx
+RT_NOCRT_BEGINPROC memrchr
+        std
+%ifdef RT_ARCH_AMD64
+ %ifdef ASM_CALL64_MSC
+        or      r8, r8
+        jz      .not_found_early
+
+        mov     r9, rdi                 ; save rdi
+        mov     eax, edx
+        lea     rdi, [rcx + r8 - 1]
+        mov     rcx, r8
+ %else
+        mov     rcx, rdx
+        jrcxz   .not_found_early
+
+        mov     eax, esi
+        lea     rdi, [rdi + rcx - 1]
+ %endif
+
+%else
+ %ifdef ASM_CALL32_WATCOM
+        mov     ecx, ebx
+        jecxz   .not_found_early
+        xchg    eax, edx
+        xchg    edi, edx                ; load + save edi
+ %else
+        mov     ecx, [esp + 0ch]
+        jecxz   .not_found_early
+        mov     edx, edi                ; save edi
+        mov     eax, [esp + 8]
+        mov     edi, [esp + 4]
+ %endif
+        lea     edi, [edi + ecx - 1]
+%endif
+
+        ; do the search
+        repne   scasb
+        jne     .not_found
+
+        ; found it
+        lea     xAX, [xDI + 1]
+%ifdef ASM_CALL64_MSC
+        mov     rdi, r9
+%endif
+%ifdef RT_ARCH_X86
+        mov     edi, edx
+%endif
+        cld
+        ret
+
+.not_found:
+%ifdef ASM_CALL64_MSC
+        mov     rdi, r9
+%endif
+%ifdef RT_ARCH_X86
+        mov     edi, edx
+%endif
+.not_found_early:
+        xor     eax, eax
+        cld
+        ret
+ENDPROC RT_NOCRT(memrchr)
+