SECTION CONTENTS
4 - 2 ADDRESS GENERATION UNIT
MOTOROLA
SECTION 4.1 ADDRESS GENERATION UNIT AND ADDRESSING MODES ....3
SECTION 4.2 AGU ARCHITECTURE ..................................................................3
4.2.1 Address Register Files (Rn) ................................................................3
4.2.2 Offset Register Files (Nn) ....................................................................4
4.2.3 Modifier Register Files (Mn) ................................................................5
4.2.4 Address ALU .......................................................................................5
4.2.5 Address Output Multiplexers ...............................................................6
SECTION 4.3 PROGRAMMING MODEL .............................................................6
4.3.1 Address Register Files (R0 - R3 and R4 - R7) ....................................7
4.3.2 Offset Register Files (N0 - N3 and N4 - N7) .......................................7
4.3.3 Modifier Register Files (M0 - M3 and M4 - M7) ...................................8
SECTION 4.4 ADDRESSING ...............................................................................8
4.4.1 Address Register Indirect Modes ........................................................9
4.4.1.1 No Update ...................................................................................9
4.4.1.2 Postincrement By 1 .....................................................................9
4.4.1.3 Postdecrement By 1 ...................................................................9
4.4.1.4 Postincrement By Offset Nn .......................................................10
4.4.1.5 Postdecrement By Offset Nn ...................................................... 11
4.4.1.6 Indexed By Offset Nn ..................................................................12
4.4.1.7 Predecrement By 1 ..................................................................... 13
4.4.2 Address Modifier Arithmetic Types .....................................................14
4.4.2.1 Linear Modifier (Mn=$FFFF) .......................................................16
4.4.2.2 Modulo Modifier .......................................................................... 18
4.4.2.3 Reverse-Carry Modifier (Mn=$0000) .......................................... 22
4.4.2.4 Address-Modifier-Type Encoding Summary ............................... 25