From 31129295c3d03908a105c8eb062d83502434bfb8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marvin=20H=C3=A4user?=
 <8659494+mhaeuser@users.noreply.github.com>
Date: Fri, 19 Mar 2021 16:35:31 +0100
Subject: [PATCH] OcCpuLib: Initial import of OcAtomicPreIncUint8

---
 Include/Acidanthera/Library/OcCpuLib.h | 13 +++++++++++++
 Library/OcCpuLib/Ia32/Atomic.nasm      | 14 ++++++++++++++
 Library/OcCpuLib/X64/Atomic.nasm       | 13 +++++++++++++
 User/Library/UserMisc.c                | 11 +++++++++++
 4 files changed, 51 insertions(+)

diff --git a/Include/Acidanthera/Library/OcCpuLib.h b/Include/Acidanthera/Library/OcCpuLib.h
index fcea2990..6d097e60 100755
--- a/Include/Acidanthera/Library/OcCpuLib.h
+++ b/Include/Acidanthera/Library/OcCpuLib.h
@@ -234,4 +234,17 @@ OcGetTSCFrequency (
   VOID
   );
 
+/**
+  Atomically pre-increment 8-bit integer.
+
+  @param[in]  Value  Pointer to 8-bit integer to increment.
+
+  @retval value before incrementing.
+**/
+UINT8
+EFIAPI
+OcAtomicPreIncUint8 (
+  IN OUT volatile UINT8  *Value
+  );
+
 #endif // OC_CPU_LIB_H_
diff --git a/Library/OcCpuLib/Ia32/Atomic.nasm b/Library/OcCpuLib/Ia32/Atomic.nasm
index 711a6371..4d278707 100644
--- a/Library/OcCpuLib/Ia32/Atomic.nasm
+++ b/Library/OcCpuLib/Ia32/Atomic.nasm
@@ -18,6 +18,20 @@ DEFAULT  REL
 
 SECTION  .text
 
+;------------------------------------------------------------------------------
+; UINT8
+; EFIAPI
+; OcAtomicPreIncUint8 (
+;   IN OUT volatile UINT8  *Value
+;   );
+;------------------------------------------------------------------------------
+global ASM_PFX(OcAtomicPreIncUint8)
+ASM_PFX(OcAtomicPreIncUint8):
+  mov       ecx, [esp + 4]
+  mov       eax, 1
+  lock xadd byte [ecx], al
+  ret
+
 ;------------------------------------------------------------------------------
 ; UINT32
 ; EFIAPI
diff --git a/Library/OcCpuLib/X64/Atomic.nasm b/Library/OcCpuLib/X64/Atomic.nasm
index 47c76ae8..07b00caa 100644
--- a/Library/OcCpuLib/X64/Atomic.nasm
+++ b/Library/OcCpuLib/X64/Atomic.nasm
@@ -18,6 +18,19 @@ DEFAULT  REL
 
 SECTION  .text
 
+;------------------------------------------------------------------------------
+; UINT8
+; EFIAPI
+; OcAtomicPreIncUint8 (
+;   IN OUT volatile UINT8  *Value
+;   );
+;------------------------------------------------------------------------------
+global ASM_PFX(OcAtomicPreIncUint8)
+ASM_PFX(OcAtomicPreIncUint8):
+  mov       eax, 1
+  lock xadd byte [rcx], al
+  ret
+
 ;------------------------------------------------------------------------------
 ; UINT32
 ; EFIAPI
diff --git a/User/Library/UserMisc.c b/User/Library/UserMisc.c
index 48ae6aed..9678df85 100644
--- a/User/Library/UserMisc.c
+++ b/User/Library/UserMisc.c
@@ -161,6 +161,17 @@ AsmCpuidEx (
   #endif
 }
 
+UINT8
+EFIAPI
+OcAtomicPreIncUint8 (
+  IN OUT volatile UINT8  *Value
+  )
+{
+  ASSERT (FALSE);
+
+  return 0;
+}
+
 UINT32
 EFIAPI
 AsmIncrementUint32 (