OSDev.org

Code: Select all

dhex_lng:
	ror ecx, 16			; swap the high & low words of ecx
dhex_s:
	push edx
	mov edx, ecx
	movzx ecx, ch			; convert high byte to 2 hex digits + 2 attrib bytes
	mov cx, [hex_lkup + ecx*2]		; get 2 bytes from lookup table
	mov al, cl				; high digit
	; Note: the high digit is supposed to be written 1st, so it ends up in dl
	stosw
	mov al, ch				; low digit
	stosw					; attrib was still in ah
	movzx ecx, dl			; now the low byte of input ecx
	mov cx, [hex_lkup + ecx*2]		; get 2 bytes from lookup table
	mov al, cl				; high digit
	stosw
	mov al, ch				; low digit
	stosw					; attrib still in ah
	mov ecx, edx
	pop edx
	ret

Code: Select all

#define ROL(Value, Times) Value = ((Value << Times) | Value >> ((sizeof(Value) << 0x03) - Times))
#define ROR(Value, Times) Value = ((Value >> Times) | Value << ((sizeof(Value) << 0x03) - Times))

Code: Select all

int rol(int value, int times)
{
  asm volatile("rol %0, %1" : "=a" (value) : "a" (value), "r" (times));
  return value;
}
int ror(int value, int times)
{
  asm volatile("ror %0, %1" : "=a" (value) : "a" (value), "r" (times));
  return value;
}

Code: Select all

void WriteHex (unsigned int InValue, unsigned int NumberofNibblesToPrint = (sizeof(unsigned int) << 0x01), 
               bool IncludeHexPrefix = true) {
  
  /* Exit the function if the number of nibbles to print is zero */
  if (NumberofNibblesToPrint == 0)
    return;

  /* Print the "0x" hexadecimal value prefix if requested */
  if (IncludeHexPrefix == true)
    printf("0x");
  
  /* If the number of  nibbles requested to be printed is more than the number of nibbles available
     in the [InValue] parameter, then set the maximum number of nibbles to the number of nibbles
     available in this parameter */
  if (NumberofNibblesToPrint >  (sizeof(InValue) << 0x01))
    NumberofNibblesToPrint = (sizeof(InValue) << 0x01);

  /* Now get the requested nibble and the nibbles to its right (if any) to the leftmost nibble of
     the value so that they can be easily extracted */
  InValue = InValue << ((sizeof(InValue) << 0x03) - (NumberofNibblesToPrint << 0x02));
  
  /* Create a acharacter buffer to take care of printing a nibble at a time */
  char CurrentChar;

  /* While there are still nibbles to be printed ... do these */
  while (NumberofNibblesToPrint-- > 0) {

    /* Get the leftmost nibble in the [CurrentChar] variable */
    CurrentChar = (char) ((InValue & 0xF0000000) >> 28) & 0x0F;

    /* If the nibble is more than 9, then it should be a character between 'A' to 'F' */
    if (CurrentChar > 9)
      CurrentChar += 7;

    /* Convert the current nibble to its equivalent character */
    CurrentChar += 48;
    
    /* Print the current nibble */
    printf("%c", CurrentChar);

    /* Get the next nibble to the leftmost nibble in the value */
    InValue = InValue << (sizeof(char) << 0x02);
  } /* while (NumberofNibblesToPrint-- > 0) { */

}