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* [PATCH v1 28/34] MdePkg/BaseSynchronizationLib: LoongArch cache related code.
@ 2022-09-08  4:52 Chao Li
  2022-09-09 17:24 ` Michael D Kinney
  0 siblings, 1 reply; 2+ messages in thread
From: Chao Li @ 2022-09-08  4:52 UTC (permalink / raw)
  To: devel; +Cc: Michael D Kinney, Liming Gao, Zhiguang Liu, Baoqi Zhang

Support LoongArch cache related functions.

Cc: Michael D Kinney <michael.d.kinney@intel.com>
Cc: Liming Gao <gaoliming@byosoft.com.cn>
Cc: Zhiguang Liu <zhiguang.liu@intel.com>

Signed-off-by: Chao Li <lichao@loongson.cn>
Co-authored-by: Baoqi Zhang <zhangbaoqi@loongson.cn>
---
 .../BaseSynchronizationLib.inf                |   5 +
 .../LoongArch64/Synchronization.c             | 246 ++++++++++++++++++
 2 files changed, 251 insertions(+)
 create mode 100644 MdePkg/Library/BaseSynchronizationLib/LoongArch64/Synchronization.c

diff --git a/MdePkg/Library/BaseSynchronizationLib/BaseSynchronizationLib.inf b/MdePkg/Library/BaseSynchronizationLib/BaseSynchronizationLib.inf
index 02ba12961a..10021f3352 100755
--- a/MdePkg/Library/BaseSynchronizationLib/BaseSynchronizationLib.inf
+++ b/MdePkg/Library/BaseSynchronizationLib/BaseSynchronizationLib.inf
@@ -4,6 +4,7 @@
 #  Copyright (c) 2007 - 2018, Intel Corporation. All rights reserved.<BR>
 #  Portions copyright (c) 2008 - 2009, Apple Inc. All rights reserved.<BR>
 #  Copyright (c) 2020, Hewlett Packard Enterprise Development LP. All rights reserved.<BR>
+#  Copyright (c) 2022, Loongson Technology Corporation Limited. All rights reserved.<BR>
 #
 #  SPDX-License-Identifier: BSD-2-Clause-Patent
 #
@@ -82,6 +83,10 @@
   Synchronization.c
   RiscV64/Synchronization.S
 
+[Sources.LOONGARCH64]
+  Synchronization.c
+  LoongArch64/Synchronization.c
+
 [Packages]
   MdePkg/MdePkg.dec
 
diff --git a/MdePkg/Library/BaseSynchronizationLib/LoongArch64/Synchronization.c b/MdePkg/Library/BaseSynchronizationLib/LoongArch64/Synchronization.c
new file mode 100644
index 0000000000..b7789f3212
--- /dev/null
+++ b/MdePkg/Library/BaseSynchronizationLib/LoongArch64/Synchronization.c
@@ -0,0 +1,246 @@
+/** @file
+  LoongArch synchronization functions.
+
+  Copyright (c) 2022, Loongson Technology Corporation Limited. All rights reserved.<BR>
+
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+
+**/
+
+#include <Library/DebugLib.h>
+
+/**
+  Performs an atomic compare exchange operation on a 16-bit
+  unsigned integer.
+
+  Performs an atomic compare exchange operation on the 16-bit
+  unsigned integer specified by Value.  If Value is equal to
+  CompareValue, then Value is set to ExchangeValue and
+  CompareValue is returned.  If Value is not equal to
+  CompareValue, then Value is returned. The compare exchange
+  operation must be performed using MP safe mechanisms.
+
+  @param[in]  Value         A pointer to the 16-bit value for the
+                        compare exchange operation.
+  @param[in]  CompareValue  16-bit value used in compare operation.
+  @param[in]  ExchangeValue 16-bit value used in exchange operation.
+
+  @return The original *Value before exchange.
+
+**/
+UINT16
+EFIAPI
+InternalSyncCompareExchange16 (
+  IN      volatile UINT16  *Value,
+  IN      UINT16           CompareValue,
+  IN      UINT16           ExchangeValue
+  )
+{
+  UINT32           RetValue;
+  UINT32           Temp;
+  UINT32           Shift;
+  UINT64           Mask;
+  UINT64           LocalCompareValue;
+  UINT64           LocalExchangeValue;
+  volatile UINT32  *Ptr32;
+
+  /* Check that ptr is naturally aligned */
+  ASSERT (!((UINT64)Value & (sizeof (Value) - 1)));
+
+  /* Mask inputs to the correct size. */
+  Mask               = (((~0UL) - (1UL << (0)) + 1) & (~0UL >> (64 - 1 - ((sizeof (UINT16) * 8) - 1))));
+  LocalCompareValue  = ((UINT64)CompareValue) & Mask;
+  LocalExchangeValue = ((UINT64)ExchangeValue) & Mask;
+
+  /*
+   * Calculate a shift & mask that correspond to the value we wish to
+   * compare & exchange within the naturally aligned 4 byte integer
+   * that includes it.
+   */
+  Shift                = (UINT64)Value & 0x3;
+  Shift               *= 8; /* BITS_PER_BYTE */
+  LocalCompareValue  <<= Shift;
+  LocalExchangeValue <<= Shift;
+  Mask               <<= Shift;
+
+  /*
+   * Calculate a pointer to the naturally aligned 4 byte integer that
+   * includes our byte of interest, and load its value.
+   */
+  Ptr32 = (UINT32 *)((UINT64)Value & ~0x3);
+
+  __asm__ __volatile__ (
+    "1:               \n"
+    "ll.w  %0, %3     \n"
+    "and   %1, %0, %4 \n"
+    "bne   %1, %5, 2f \n"
+    "andn  %1, %0, %4 \n"
+    "or    %1, %1, %6 \n"
+    "sc.w  %1, %2     \n"
+    "beqz  %1, 1b     \n"
+    "b     3f         \n"
+    "2:               \n"
+    "dbar  0          \n"
+    "3:               \n"
+    : "=&r" (RetValue), "=&r" (Temp), "=" "ZC" (*Ptr32)
+    : "ZC" (*Ptr32), "Jr" (Mask), "Jr" (LocalCompareValue), "Jr" (LocalExchangeValue)
+    : "memory"
+  );
+
+  return (RetValue & Mask) >> Shift;
+}
+
+/**
+  Performs an atomic compare exchange operation on a 32-bit
+  unsigned integer.
+
+  Performs an atomic compare exchange operation on the 32-bit
+  unsigned integer specified by Value.  If Value is equal to
+  CompareValue, then Value is set to ExchangeValue and
+  CompareValue is returned.  If Value is not equal to
+  CompareValue, then Value is returned. The compare exchange
+  operation must be performed using MP safe mechanisms.
+
+  @param[in]  Value         A pointer to the 32-bit value for the
+                        compare exchange operation.
+  @param[in]  CompareValue  32-bit value used in compare operation.
+  @param[in]  ExchangeValue 32-bit value used in exchange operation.
+
+  @return The original *Value before exchange.
+
+**/
+UINT32
+EFIAPI
+InternalSyncCompareExchange32 (
+  IN      volatile UINT32  *Value,
+  IN      UINT32           CompareValue,
+  IN      UINT32           ExchangeValue
+  )
+{
+  UINT32  RetValue;
+
+  __asm__ __volatile__ (
+    "1:              \n"
+    "ll.w %0, %2     \n"
+    "bne  %0, %3, 2f \n"
+    "move %0, %4     \n"
+    "sc.w %0, %1     \n"
+    "beqz %0, 1b     \n"
+    "b    3f         \n"
+    "2:              \n"
+    "dbar 0          \n"
+    "3:              \n"
+    : "=&r" (RetValue), "=" "ZC" (*Value)
+    : "ZC" (*Value), "Jr" (CompareValue), "Jr" (ExchangeValue)
+    : "memory"
+  );
+  return RetValue;
+}
+
+/**
+  Performs an atomic compare exchange operation on a 64-bit unsigned integer.
+
+  Performs an atomic compare exchange operation on the 64-bit unsigned integer specified
+  by Value.  If Value is equal to CompareValue, then Value is set to ExchangeValue and
+  CompareValue is returned.  If Value is not equal to CompareValue, then Value is returned.
+  The compare exchange operation must be performed using MP safe mechanisms.
+
+  @param[in]  Value         A pointer to the 64-bit value for the compare exchange
+                        operation.
+  @param[in]  CompareValue  64-bit value used in compare operation.
+  @param[in]  ExchangeValue 64-bit value used in exchange operation.
+
+  @return The original *Value before exchange.
+
+**/
+UINT64
+EFIAPI
+InternalSyncCompareExchange64 (
+  IN      volatile UINT64  *Value,
+  IN      UINT64           CompareValue,
+  IN      UINT64           ExchangeValue
+  )
+{
+  UINT64  RetValue;
+
+  __asm__ __volatile__ (
+    "1:              \n"
+    "ll.d %0, %2     \n"
+    "bne  %0, %3, 2f \n"
+    "move %0, %4     \n"
+    "sc.d %0, %1     \n"
+    "beqz %0, 1b     \n"
+    "b    3f         \n"
+    "2:              \n"
+    "dbar 0          \n"
+    "3:              \n"
+    : "=&r" (RetValue), "=" "ZC" (*Value)
+    : "ZC" (*Value), "Jr" (CompareValue), "Jr" (ExchangeValue)
+    : "memory"
+  );
+  return RetValue;
+}
+
+/**
+  Performs an atomic increment of an 32-bit unsigned integer.
+
+  Performs an atomic increment of the 32-bit unsigned integer specified by
+  Value and returns the incremented value. The increment operation must be
+  performed using MP safe mechanisms. The state of the return value is not
+  guaranteed to be MP safe.
+
+  @param[in]  Value A pointer to the 32-bit value to increment.
+
+  @return The incremented value.
+
+**/
+UINT32
+EFIAPI
+InternalSyncIncrement (
+  IN      volatile UINT32  *Value
+  )
+{
+  UINT32  Temp;
+
+  Temp = *Value;
+  __asm__ __volatile__ (
+     "dbar    0          \n"
+     "amadd.w %1, %2, %0 \n"
+     : "+ZB" (*Value), "=&r" (Temp)
+     : "r" (1)
+     : "memory"
+  );
+  return *Value;
+}
+
+/**
+  Performs an atomic decrement of an 32-bit unsigned integer.
+
+  Performs an atomic decrement of the 32-bit unsigned integer specified by
+  Value and returns the decrement value. The decrement operation must be
+  performed using MP safe mechanisms. The state of the return value is not
+  guaranteed to be MP safe.
+
+  @param[in]  Value A pointer to the 32-bit value to decrement.
+
+  @return The decrement value.
+
+**/
+UINT32
+EFIAPI
+InternalSyncDecrement (
+  IN      volatile UINT32  *Value
+  )
+{
+  UINT32  Temp;
+
+  Temp = *Value;
+  __asm__ __volatile__ (
+     "dbar    0          \n"
+     "amadd.w %1, %2, %0 \n"
+     : "+ZB" (*Value), "=&r" (Temp)
+     : "r" (-1)
+     : "memory"
+  );
+  return *Value;
+}
-- 
2.27.0


^ permalink raw reply related	[flat|nested] 2+ messages in thread

* Re: [PATCH v1 28/34] MdePkg/BaseSynchronizationLib: LoongArch cache related code.
  2022-09-08  4:52 [PATCH v1 28/34] MdePkg/BaseSynchronizationLib: LoongArch cache related code Chao Li
@ 2022-09-09 17:24 ` Michael D Kinney
  0 siblings, 0 replies; 2+ messages in thread
From: Michael D Kinney @ 2022-09-09 17:24 UTC (permalink / raw)
  To: Chao Li, devel@edk2.groups.io, Kinney, Michael D
  Cc: Gao, Liming, Liu, Zhiguang, Baoqi Zhang

Recommend converting inline assembly to .S.

Mike

> -----Original Message-----
> From: Chao Li <lichao@loongson.cn>
> Sent: Wednesday, September 7, 2022 9:52 PM
> To: devel@edk2.groups.io
> Cc: Kinney, Michael D <michael.d.kinney@intel.com>; Gao, Liming <gaoliming@byosoft.com.cn>; Liu, Zhiguang
> <zhiguang.liu@intel.com>; Baoqi Zhang <zhangbaoqi@loongson.cn>
> Subject: [PATCH v1 28/34] MdePkg/BaseSynchronizationLib: LoongArch cache related code.
> 
> Support LoongArch cache related functions.
> 
> Cc: Michael D Kinney <michael.d.kinney@intel.com>
> Cc: Liming Gao <gaoliming@byosoft.com.cn>
> Cc: Zhiguang Liu <zhiguang.liu@intel.com>
> 
> Signed-off-by: Chao Li <lichao@loongson.cn>
> Co-authored-by: Baoqi Zhang <zhangbaoqi@loongson.cn>
> ---
>  .../BaseSynchronizationLib.inf                |   5 +
>  .../LoongArch64/Synchronization.c             | 246 ++++++++++++++++++
>  2 files changed, 251 insertions(+)
>  create mode 100644 MdePkg/Library/BaseSynchronizationLib/LoongArch64/Synchronization.c
> 
> diff --git a/MdePkg/Library/BaseSynchronizationLib/BaseSynchronizationLib.inf
> b/MdePkg/Library/BaseSynchronizationLib/BaseSynchronizationLib.inf
> index 02ba12961a..10021f3352 100755
> --- a/MdePkg/Library/BaseSynchronizationLib/BaseSynchronizationLib.inf
> +++ b/MdePkg/Library/BaseSynchronizationLib/BaseSynchronizationLib.inf
> @@ -4,6 +4,7 @@
>  #  Copyright (c) 2007 - 2018, Intel Corporation. All rights reserved.<BR>
> 
>  #  Portions copyright (c) 2008 - 2009, Apple Inc. All rights reserved.<BR>
> 
>  #  Copyright (c) 2020, Hewlett Packard Enterprise Development LP. All rights reserved.<BR>
> 
> +#  Copyright (c) 2022, Loongson Technology Corporation Limited. All rights reserved.<BR>
> 
>  #
> 
>  #  SPDX-License-Identifier: BSD-2-Clause-Patent
> 
>  #
> 
> @@ -82,6 +83,10 @@
>    Synchronization.c
> 
>    RiscV64/Synchronization.S
> 
> 
> 
> +[Sources.LOONGARCH64]
> 
> +  Synchronization.c
> 
> +  LoongArch64/Synchronization.c
> 
> +
> 
>  [Packages]
> 
>    MdePkg/MdePkg.dec
> 
> 
> 
> diff --git a/MdePkg/Library/BaseSynchronizationLib/LoongArch64/Synchronization.c
> b/MdePkg/Library/BaseSynchronizationLib/LoongArch64/Synchronization.c
> new file mode 100644
> index 0000000000..b7789f3212
> --- /dev/null
> +++ b/MdePkg/Library/BaseSynchronizationLib/LoongArch64/Synchronization.c
> @@ -0,0 +1,246 @@
> +/** @file
> 
> +  LoongArch synchronization functions.
> 
> +
> 
> +  Copyright (c) 2022, Loongson Technology Corporation Limited. All rights reserved.<BR>
> 
> +
> 
> +  SPDX-License-Identifier: BSD-2-Clause-Patent
> 
> +
> 
> +**/
> 
> +
> 
> +#include <Library/DebugLib.h>
> 
> +
> 
> +/**
> 
> +  Performs an atomic compare exchange operation on a 16-bit
> 
> +  unsigned integer.
> 
> +
> 
> +  Performs an atomic compare exchange operation on the 16-bit
> 
> +  unsigned integer specified by Value.  If Value is equal to
> 
> +  CompareValue, then Value is set to ExchangeValue and
> 
> +  CompareValue is returned.  If Value is not equal to
> 
> +  CompareValue, then Value is returned. The compare exchange
> 
> +  operation must be performed using MP safe mechanisms.
> 
> +
> 
> +  @param[in]  Value         A pointer to the 16-bit value for the
> 
> +                        compare exchange operation.
> 
> +  @param[in]  CompareValue  16-bit value used in compare operation.
> 
> +  @param[in]  ExchangeValue 16-bit value used in exchange operation.
> 
> +
> 
> +  @return The original *Value before exchange.
> 
> +
> 
> +**/
> 
> +UINT16
> 
> +EFIAPI
> 
> +InternalSyncCompareExchange16 (
> 
> +  IN      volatile UINT16  *Value,
> 
> +  IN      UINT16           CompareValue,
> 
> +  IN      UINT16           ExchangeValue
> 
> +  )
> 
> +{
> 
> +  UINT32           RetValue;
> 
> +  UINT32           Temp;
> 
> +  UINT32           Shift;
> 
> +  UINT64           Mask;
> 
> +  UINT64           LocalCompareValue;
> 
> +  UINT64           LocalExchangeValue;
> 
> +  volatile UINT32  *Ptr32;
> 
> +
> 
> +  /* Check that ptr is naturally aligned */
> 
> +  ASSERT (!((UINT64)Value & (sizeof (Value) - 1)));
> 
> +
> 
> +  /* Mask inputs to the correct size. */
> 
> +  Mask               = (((~0UL) - (1UL << (0)) + 1) & (~0UL >> (64 - 1 - ((sizeof (UINT16) * 8) - 1))));
> 
> +  LocalCompareValue  = ((UINT64)CompareValue) & Mask;
> 
> +  LocalExchangeValue = ((UINT64)ExchangeValue) & Mask;
> 
> +
> 
> +  /*
> 
> +   * Calculate a shift & mask that correspond to the value we wish to
> 
> +   * compare & exchange within the naturally aligned 4 byte integer
> 
> +   * that includes it.
> 
> +   */
> 
> +  Shift                = (UINT64)Value & 0x3;
> 
> +  Shift               *= 8; /* BITS_PER_BYTE */
> 
> +  LocalCompareValue  <<= Shift;
> 
> +  LocalExchangeValue <<= Shift;
> 
> +  Mask               <<= Shift;
> 
> +
> 
> +  /*
> 
> +   * Calculate a pointer to the naturally aligned 4 byte integer that
> 
> +   * includes our byte of interest, and load its value.
> 
> +   */
> 
> +  Ptr32 = (UINT32 *)((UINT64)Value & ~0x3);
> 
> +
> 
> +  __asm__ __volatile__ (
> 
> +    "1:               \n"
> 
> +    "ll.w  %0, %3     \n"
> 
> +    "and   %1, %0, %4 \n"
> 
> +    "bne   %1, %5, 2f \n"
> 
> +    "andn  %1, %0, %4 \n"
> 
> +    "or    %1, %1, %6 \n"
> 
> +    "sc.w  %1, %2     \n"
> 
> +    "beqz  %1, 1b     \n"
> 
> +    "b     3f         \n"
> 
> +    "2:               \n"
> 
> +    "dbar  0          \n"
> 
> +    "3:               \n"
> 
> +    : "=&r" (RetValue), "=&r" (Temp), "=" "ZC" (*Ptr32)
> 
> +    : "ZC" (*Ptr32), "Jr" (Mask), "Jr" (LocalCompareValue), "Jr" (LocalExchangeValue)
> 
> +    : "memory"
> 
> +  );
> 
> +
> 
> +  return (RetValue & Mask) >> Shift;
> 
> +}
> 
> +
> 
> +/**
> 
> +  Performs an atomic compare exchange operation on a 32-bit
> 
> +  unsigned integer.
> 
> +
> 
> +  Performs an atomic compare exchange operation on the 32-bit
> 
> +  unsigned integer specified by Value.  If Value is equal to
> 
> +  CompareValue, then Value is set to ExchangeValue and
> 
> +  CompareValue is returned.  If Value is not equal to
> 
> +  CompareValue, then Value is returned. The compare exchange
> 
> +  operation must be performed using MP safe mechanisms.
> 
> +
> 
> +  @param[in]  Value         A pointer to the 32-bit value for the
> 
> +                        compare exchange operation.
> 
> +  @param[in]  CompareValue  32-bit value used in compare operation.
> 
> +  @param[in]  ExchangeValue 32-bit value used in exchange operation.
> 
> +
> 
> +  @return The original *Value before exchange.
> 
> +
> 
> +**/
> 
> +UINT32
> 
> +EFIAPI
> 
> +InternalSyncCompareExchange32 (
> 
> +  IN      volatile UINT32  *Value,
> 
> +  IN      UINT32           CompareValue,
> 
> +  IN      UINT32           ExchangeValue
> 
> +  )
> 
> +{
> 
> +  UINT32  RetValue;
> 
> +
> 
> +  __asm__ __volatile__ (
> 
> +    "1:              \n"
> 
> +    "ll.w %0, %2     \n"
> 
> +    "bne  %0, %3, 2f \n"
> 
> +    "move %0, %4     \n"
> 
> +    "sc.w %0, %1     \n"
> 
> +    "beqz %0, 1b     \n"
> 
> +    "b    3f         \n"
> 
> +    "2:              \n"
> 
> +    "dbar 0          \n"
> 
> +    "3:              \n"
> 
> +    : "=&r" (RetValue), "=" "ZC" (*Value)
> 
> +    : "ZC" (*Value), "Jr" (CompareValue), "Jr" (ExchangeValue)
> 
> +    : "memory"
> 
> +  );
> 
> +  return RetValue;
> 
> +}
> 
> +
> 
> +/**
> 
> +  Performs an atomic compare exchange operation on a 64-bit unsigned integer.
> 
> +
> 
> +  Performs an atomic compare exchange operation on the 64-bit unsigned integer specified
> 
> +  by Value.  If Value is equal to CompareValue, then Value is set to ExchangeValue and
> 
> +  CompareValue is returned.  If Value is not equal to CompareValue, then Value is returned.
> 
> +  The compare exchange operation must be performed using MP safe mechanisms.
> 
> +
> 
> +  @param[in]  Value         A pointer to the 64-bit value for the compare exchange
> 
> +                        operation.
> 
> +  @param[in]  CompareValue  64-bit value used in compare operation.
> 
> +  @param[in]  ExchangeValue 64-bit value used in exchange operation.
> 
> +
> 
> +  @return The original *Value before exchange.
> 
> +
> 
> +**/
> 
> +UINT64
> 
> +EFIAPI
> 
> +InternalSyncCompareExchange64 (
> 
> +  IN      volatile UINT64  *Value,
> 
> +  IN      UINT64           CompareValue,
> 
> +  IN      UINT64           ExchangeValue
> 
> +  )
> 
> +{
> 
> +  UINT64  RetValue;
> 
> +
> 
> +  __asm__ __volatile__ (
> 
> +    "1:              \n"
> 
> +    "ll.d %0, %2     \n"
> 
> +    "bne  %0, %3, 2f \n"
> 
> +    "move %0, %4     \n"
> 
> +    "sc.d %0, %1     \n"
> 
> +    "beqz %0, 1b     \n"
> 
> +    "b    3f         \n"
> 
> +    "2:              \n"
> 
> +    "dbar 0          \n"
> 
> +    "3:              \n"
> 
> +    : "=&r" (RetValue), "=" "ZC" (*Value)
> 
> +    : "ZC" (*Value), "Jr" (CompareValue), "Jr" (ExchangeValue)
> 
> +    : "memory"
> 
> +  );
> 
> +  return RetValue;
> 
> +}
> 
> +
> 
> +/**
> 
> +  Performs an atomic increment of an 32-bit unsigned integer.
> 
> +
> 
> +  Performs an atomic increment of the 32-bit unsigned integer specified by
> 
> +  Value and returns the incremented value. The increment operation must be
> 
> +  performed using MP safe mechanisms. The state of the return value is not
> 
> +  guaranteed to be MP safe.
> 
> +
> 
> +  @param[in]  Value A pointer to the 32-bit value to increment.
> 
> +
> 
> +  @return The incremented value.
> 
> +
> 
> +**/
> 
> +UINT32
> 
> +EFIAPI
> 
> +InternalSyncIncrement (
> 
> +  IN      volatile UINT32  *Value
> 
> +  )
> 
> +{
> 
> +  UINT32  Temp;
> 
> +
> 
> +  Temp = *Value;
> 
> +  __asm__ __volatile__ (
> 
> +     "dbar    0          \n"
> 
> +     "amadd.w %1, %2, %0 \n"
> 
> +     : "+ZB" (*Value), "=&r" (Temp)
> 
> +     : "r" (1)
> 
> +     : "memory"
> 
> +  );
> 
> +  return *Value;
> 
> +}
> 
> +
> 
> +/**
> 
> +  Performs an atomic decrement of an 32-bit unsigned integer.
> 
> +
> 
> +  Performs an atomic decrement of the 32-bit unsigned integer specified by
> 
> +  Value and returns the decrement value. The decrement operation must be
> 
> +  performed using MP safe mechanisms. The state of the return value is not
> 
> +  guaranteed to be MP safe.
> 
> +
> 
> +  @param[in]  Value A pointer to the 32-bit value to decrement.
> 
> +
> 
> +  @return The decrement value.
> 
> +
> 
> +**/
> 
> +UINT32
> 
> +EFIAPI
> 
> +InternalSyncDecrement (
> 
> +  IN      volatile UINT32  *Value
> 
> +  )
> 
> +{
> 
> +  UINT32  Temp;
> 
> +
> 
> +  Temp = *Value;
> 
> +  __asm__ __volatile__ (
> 
> +     "dbar    0          \n"
> 
> +     "amadd.w %1, %2, %0 \n"
> 
> +     : "+ZB" (*Value), "=&r" (Temp)
> 
> +     : "r" (-1)
> 
> +     : "memory"
> 
> +  );
> 
> +  return *Value;
> 
> +}
> 
> --
> 2.27.0


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