## EX = Expand Register

Hex | Mnemonic | Cycles
--- | --- | ---
CE A8 | EX BA, A | 12

### Execute

    A       =  (8-Bits) Register A
    BA      = (16-Bits) Register BA: (B shl 8) or A

    ; EX BA, A
    ;
    ; BA = Destination
    ; A  = Source

    IF (A AND 0x80) THEN  ; Check for sign
      B = 0xFF
    ELSE
      B = 0x00
    ENDIF

### Description

EX expands register A into BA, turning a signed 8-bits value into 16-bits.

### Conditions

None

### Examples

    ; A = 0x05 (5)
    EX BA, A
    ; BA = 0x0005 (5)

    ; A = 0xF9 (-7)
    EX BA, A
    ; BA = 0xFFF9 (-7)

    ; A = 0x00 (0)
    EX BA, A
    ; BA = 0x0000 (0)

    ; A = 0x7F (127)
    EX BA, A
    ; BA = 0x007F (127)

    ; A = 0x80 (-128)
    EX BA, A
    ; BA = 0xFF80 (-128)

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