SH7059 Datasheet, PDF (119/1042 Pages) Renesas Technology Corp – 32-Bit RISC Microcomputer

2. CPU
2.2.2 Data Formats in Memory
Memory data formats are classified into bytes, words, and longwords. Byte data can be accessed from any address, but an
address error will occur if an attempt is made to access word data starting from an address other than 2n or longword data
starting from an address other than 4n. In such cases, the data accessed cannot be guaranteed. The hardware stack area,
referred to by the hardware stack pointer (SP, R15), uses only longword data starting from address 4n because this area
holds the program counter and status register (figure 2.7).
Address 2n
Address 4n
Address m + 1 Address m + 3
Address m
Address m + 2
31
23
15
7
0
Byte Byte Byte Byte
Word
Word
Longword
Figure 2.7 Data Formats in Memory
2.2.3 Immediate Data Format
Byte (8 bit) immediate data resides in an instruction code. Immediate data accessed by the MOV, ADD, and CMP/EQ
instructions is sign-extended and handled in registers as longword data. Immediate data accessed by the TST, AND, OR,
and XOR instructions is zero-extended and handled as longword data. Consequently, AND instructions with immediate
data always clear the upper 24 bits of the destination register.
Word or longword immediate data is not located in the instruction code, but instead is stored in a memory table. An
immediate data transfer instruction (MOV) accesses the memory table using the PC relative addressing mode with
displacement.
2.3 Instruction Features
2.3.1 RISC-Type Instruction Set
All instructions are RISC type. This section details their functions.
16-Bit Fixed Length: All instructions are 16 bits long, increasing program code efficiency.
One Instruction per Cycle: The microprocessor can execute basic instructions in one cycle using the pipeline system.
Instructions are executed in 12.5 ns at 80 MHz.
Data Length: Longword is the standard data length for all operations. Memory can be accessed in bytes, words, or
longwords. Byte or word data accessed from memory is sign-extended and handled as longword data. Immediate data is
sign-extended for arithmetic operations or zero-extended for logic operations. It also is handled as longword data (table
2.2).
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