| 摘要 |
A data processing system (10) performs indexed addressing, autoincrementing, and autodecrementing using power of two byte boundaries. For example, a 5-bit offset allows a user to progress sixteen bytes either forward or backward through a table of data. An instruction specifying an operation to be performed, a pointer register (58, 60), and an offset value is provided to an execution unit (14). The pointer register (58, 60) stores a first address value and the offset value has a sign and a magnitude. An arithmetic logic unit, ALU, (52) inverts the sign of the offset value to provide an inverted sign value. A plurality of adders (100, 102, 104, 106, and 108) adds the offset value, the first address value, and the inverted sign value to generate an offset sum. A positive offset value is increased by one to generate a symmetric power of two offset range. <IMAGE>
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