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S3C8245/P8245/C8249/P8249 INSTRUCTION SET
6-1
6 INSTRUCTION SET
OVERVIEW
The SAM8 instruction set is specifically designed to support the large register files that are typical of most SAM8
microcontrollers. There are 78 instructions. The powerful data manipulation capabilities and features of the
instruction set include:
— A full complement of 8-bit arithmetic and logic operations, including multiply and divide
— No special I/O instructions (I/O control/data registers are mapped directly into the register file)
— Decimal adjustment included in binary-coded decimal (BCD) operations
— 16-bit (word) data can be incremented and decremented
— Flexible instructions for bit addressing, rotate, and shift operations
DATA TYPES
The SAM8 CPU performs operations on bits, bytes, BCD digits, and two-byte words. Bits in the register file can be
set, cleared, complemented, and tested. Bits within a byte are numbered from 7 to 0, where bit 0 is the least
significant (right-most) bit.
REGISTER ADDRESSING
To access an individual register, an 8-bit address in the range 0-255 or the 4-bit address of a working register is
specified. Paired registers can be used to construct 16-bit data or 16-bit program memory or data memory
addresses. For detailed information about register addressing, please refer to Section 2, "Address Spaces."
ADDRESSING MODES
There are seven explicit addressing modes: Register (R), Indirect Register (IR), Indexed (X), Direct (DA), Relative
(RA), Immediate (IM), and Indirect (IA). For detailed descriptions of these addressing modes, please refer to Section
3, "Addressing Modes."