SetMem.c

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#include "MemLibInternals.h"
 
VOID *
EFIAPI
InternalMemSetMem (
  OUT     VOID   *Buffer,
  IN      UINTN  Length,
  IN      UINT8  Value
  )
{
  //
  // Declare the local variables that actually move the data elements as
  // volatile to prevent the optimizer from replacing this function with
  // the intrinsic memset()
  //
  volatile UINT8   *Pointer8;
  volatile UINT32  *Pointer32;
  volatile UINT64  *Pointer64;
  UINT32           Value32;
  UINT64           Value64;
 
  if ((((UINTN)Buffer & 0x7) == 0) && (Length >= 8)) {
    // Generate the 64bit value
    Value32 = (Value << 24) | (Value << 16) | (Value << 8) | Value;
    Value64 = LShiftU64 (Value32, 32) | Value32;
 
    Pointer64 = (UINT64 *)Buffer;
    while (Length >= 8) {
      *(Pointer64++) = Value64;
      Length        -= 8;
    }
 
    // Finish with bytes if needed
    Pointer8 = (UINT8 *)Pointer64;
  } else if ((((UINTN)Buffer & 0x3) == 0) && (Length >= 4)) {
    // Generate the 32bit value
    Value32 = (Value << 24) | (Value << 16) | (Value << 8) | Value;
 
    Pointer32 = (UINT32 *)Buffer;
    while (Length >= 4) {
      *(Pointer32++) = Value32;
      Length        -= 4;
    }
 
    // Finish with bytes if needed
    Pointer8 = (UINT8 *)Pointer32;
  } else {
    Pointer8 = (UINT8 *)Buffer;
  }
 
  while (Length-- > 0) {
    *(Pointer8++) = Value;
  }
 
  return Buffer;
}