audk/MdePkg/Library/UefiMemoryLib/MemLibGeneric.c

/** @file
  Architecture Independent Base Memory Library Implementation.

  The following BaseMemoryLib instances contain the same copy of this file:
    BaseMemoryLib
    PeiMemoryLib
    UefiMemoryLib

  Copyright (c) 2006 - 2016, Intel Corporation. All rights reserved.<BR>
  SPDX-License-Identifier: BSD-2-Clause-Patent

**/

#include "MemLibInternals.h"

/**
  Fills a target buffer with a 16-bit value, and returns the target buffer.

  @param  Buffer  The pointer to the target buffer to fill.
  @param  Length  The count of 16-bit value to fill.
  @param  Value   The value with which to fill Length bytes of Buffer.

  @return Buffer

**/
VOID *
EFIAPI
InternalMemSetMem16 (
  OUT     VOID                      *Buffer,
  IN      UINTN                     Length,
  IN      UINT16                    Value
  )
{
  for (; Length != 0; Length--) {
    ((UINT16*)Buffer)[Length - 1] = Value;
  }
  return Buffer;
}

/**
  Fills a target buffer with a 32-bit value, and returns the target buffer.

  @param  Buffer  The pointer to the target buffer to fill.
  @param  Length  The count of 32-bit value to fill.
  @param  Value   The value with which to fill Length bytes of Buffer.

  @return Buffer

**/
VOID *
EFIAPI
InternalMemSetMem32 (
  OUT     VOID                      *Buffer,
  IN      UINTN                     Length,
  IN      UINT32                    Value
  )
{
  for (; Length != 0; Length--) {
    ((UINT32*)Buffer)[Length - 1] = Value;
  }
  return Buffer;
}

/**
  Fills a target buffer with a 64-bit value, and returns the target buffer.

  @param  Buffer  The pointer to the target buffer to fill.
  @param  Length  The count of 64-bit value to fill.
  @param  Value   The value with which to fill Length bytes of Buffer.

  @return Buffer

**/
VOID *
EFIAPI
InternalMemSetMem64 (
  OUT     VOID                      *Buffer,
  IN      UINTN                     Length,
  IN      UINT64                    Value
  )
{
  for (; Length != 0; Length--) {
    ((UINT64*)Buffer)[Length - 1] = Value;
  }
  return Buffer;
}

/**
  Set Buffer to 0 for Size bytes.

  @param  Buffer Memory to set.
  @param  Length The number of bytes to set

  @return Buffer

**/
VOID *
EFIAPI
InternalMemZeroMem (
  OUT     VOID                      *Buffer,
  IN      UINTN                     Length
  )
{
  return InternalMemSetMem (Buffer, Length, 0);
}

/**
  Compares two memory buffers of a given length.

  @param  DestinationBuffer The first memory buffer
  @param  SourceBuffer      The second memory buffer
  @param  Length            The length of DestinationBuffer and SourceBuffer memory
                            regions to compare. Must be non-zero.

  @return 0                 All Length bytes of the two buffers are identical.
  @retval Non-zero          The first mismatched byte in SourceBuffer subtracted from the first
                            mismatched byte in DestinationBuffer.

**/
INTN
EFIAPI
InternalMemCompareMem (
  IN      CONST VOID                *DestinationBuffer,
  IN      CONST VOID                *SourceBuffer,
  IN      UINTN                     Length
  )
{
  while ((--Length != 0) &&
         (*(INT8*)DestinationBuffer == *(INT8*)SourceBuffer)) {
    DestinationBuffer = (INT8*)DestinationBuffer + 1;
    SourceBuffer = (INT8*)SourceBuffer + 1;
  }
  return (INTN)*(UINT8*)DestinationBuffer - (INTN)*(UINT8*)SourceBuffer;
}

/**
  Scans a target buffer for an 8-bit value, and returns a pointer to the
  matching 8-bit value in the target buffer.

  @param  Buffer  The pointer to the target buffer to scan.
  @param  Length  The count of 8-bit value to scan. Must be non-zero.
  @param  Value   The value to search for in the target buffer.

  @return The pointer to the first occurrence or NULL if not found.

**/
CONST VOID *
EFIAPI
InternalMemScanMem8 (
  IN      CONST VOID                *Buffer,
  IN      UINTN                     Length,
  IN      UINT8                     Value
  )
{
  CONST UINT8                       *Pointer;

  Pointer = (CONST UINT8*)Buffer;
  do {
    if (*(Pointer++) == Value) {
      return --Pointer;
    }
  } while (--Length != 0);
  return NULL;
}

/**
  Scans a target buffer for a 16-bit value, and returns a pointer to the
  matching 16-bit value in the target buffer.

  @param  Buffer  The pointer to the target buffer to scan.
  @param  Length  The count of 16-bit value to scan. Must be non-zero.
  @param  Value   The value to search for in the target buffer.

  @return The pointer to the first occurrence or NULL if not found.

**/
CONST VOID *
EFIAPI
InternalMemScanMem16 (
  IN      CONST VOID                *Buffer,
  IN      UINTN                     Length,
  IN      UINT16                    Value
  )
{
  CONST UINT16                      *Pointer;

  Pointer = (CONST UINT16*)Buffer;
  do {
    if (*(Pointer++) == Value) {
      return --Pointer;
    }
  } while (--Length != 0);
  return NULL;
}

/**
  Scans a target buffer for a 32-bit value, and returns a pointer to the
  matching 32-bit value in the target buffer.

  @param  Buffer  The pointer to the target buffer to scan.
  @param  Length  The count of 32-bit value to scan. Must be non-zero.
  @param  Value   The value to search for in the target buffer.

  @return The pointer to the first occurrence or NULL if not found.

**/
CONST VOID *
EFIAPI
InternalMemScanMem32 (
  IN      CONST VOID                *Buffer,
  IN      UINTN                     Length,
  IN      UINT32                    Value
  )
{
  CONST UINT32                      *Pointer;

  Pointer = (CONST UINT32*)Buffer;
  do {
    if (*(Pointer++) == Value) {
      return --Pointer;
    }
  } while (--Length != 0);
  return NULL;
}

/**
  Scans a target buffer for a 64-bit value, and returns a pointer to the
  matching 64-bit value in the target buffer.

  @param  Buffer  The pointer to the target buffer to scan.
  @param  Length  The count of 64-bit value to scan. Must be non-zero.
  @param  Value   The value to search for in the target buffer.

  @return The pointer to the first occurrence or NULL if not found.

**/
CONST VOID *
EFIAPI
InternalMemScanMem64 (
  IN      CONST VOID                *Buffer,
  IN      UINTN                     Length,
  IN      UINT64                    Value
  )
{
  CONST UINT64                      *Pointer;

  Pointer = (CONST UINT64*)Buffer;
  do {
    if (*(Pointer++) == Value) {
      return --Pointer;
    }
  } while (--Length != 0);
  return NULL;
}

/**
  Checks whether the contents of a buffer are all zeros.

  @param  Buffer  The pointer to the buffer to be checked.
  @param  Length  The size of the buffer (in bytes) to be checked.

  @retval TRUE    Contents of the buffer are all zeros.
  @retval FALSE   Contents of the buffer are not all zeros.

**/
BOOLEAN
EFIAPI
InternalMemIsZeroBuffer (
  IN CONST VOID  *Buffer,
  IN UINTN       Length
  )
{
  CONST UINT8 *BufferData;
  UINTN       Index;

  BufferData = Buffer;
  for (Index = 0; Index < Length; Index++) {
    if (BufferData[Index] != 0) {
      return FALSE;
    }
  }
  return TRUE;
}