In SX Microcontrollers, SX/B Compiler and SX-Key Tool, JonnyMac wrote:

Most times simpler is better.  Consider these three (dirt simple) functions that do what you want.  They are easy to use and don't require any program variables -- the functionality is so simple it can be handled in assembly using SX/B's internal parameter variables.

[code]NIB_LO          FUNC    1, 2, 2, Byte, Byte, Byte
NIB_HI          FUNC    1, 2, 2, Byte, Byte, Byte
MERGE           FUNC    1, 2, 2, Byte, Byte, Byte[/code]

[code]' Use: bResult = NIB_LO target, value
' -- moves value into low nibble of target
' -- value truncated to four bits

FUNC NIB_LO
  ASM
    AND   __param1, #$F0                        ' clear low nib
    AND   __param2, #$0F                        ' truncate to 4 bits
    OR    __param1, __param2                    ' merge
  ENDASM
  ENDFUNC


' Use: bResult = NIB_HI target, value
' -- moves value into high nibble of target
' -- value truncated to four bits

FUNC NIB_HI
  ASM
    AND   __param1, #$0F                        ' clear high nib
    AND   __param2, #$0F                        ' truncate to 4 bits
    SWAP  __param2                              ' move value to high nib
    OR    __param1, __param2                    ' merge
  ENDASM
  ENDFUNC


' Use: bResult = MERGE value1, value2
' -- merge two 4-bit values into a byte
' -- value1 to high nibble, value2 to low nibble
' -- values truncated to four bits

FUNC MERGE
  ASM
    AND   __param1, #$0F                        ' truncate to 4 bits
    SWAP  __param1                              ' move to high nibble
    AND   __param2, #$0F                        ' truncate to 4 bits
    OR    __param1, __param2                    ' merge
  ENDASM
  ENDFUNC[/code]

I know, I know... Assembly is supposed to be "hard."  Well, it really isn't and I am frequently adding very efficient Assembly sections to my SX/B programs.

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