M32C8A Datasheet, PDF (36/372 Pages) Renesas Technology Corp – RENESAS MCU M16C FAMILY / M32C/80 Series

M32C/8A Group
2. Central Processing Unit (CPU)
2.1 General Registers
2.1.1 Data Registers (R0, R1, R2, and R3)
R0, R1, R2, and R3 are 16-bit registers for transfer, arithmetic and logic operations. R0 and R1 can be split into
high-order (R0H/R1H) and low-order bits (R0L/R1L) to be used separately as 8-bit data registers.
R0 can be combined with R2 and used as a 32-bit data register (R2R0). The same applies to R3R1.
2.1.2 Address Registers (A0 and A1)
A0 and A1 are 24-bit registers used for A0-/A1-indirect addressing, A0-/A1-relative addressing, transfer,
arithmetic and logic operations.
2.1.3 Static Base Register (SB)
SB is a 24-bit register used for SB-relative addressing.
2.1.4 Frame Base Register (FB)
FB is a 24-bit register used for FB-relative addressing.
2.1.5 User Stack Pointer (USP) and Interrupt Stack Pointer (ISP)
The stack pointers (SP), USP and ISP, are 24 bits wide each. The U flag is used to switch between USP and ISP.
Refer to 2.1.8 Flag Register (FLG) for details on the U flag. Set USP and ISP to even addresses to execute an
interrupt sequence efficiently.
2.1.6 Interrupt Table Register (INTB)
INTB is a 24-bit register indicating the starting address of a relocatable interrupt vector table.
2.1.7 Program Counter (PC)
PC is 24 bits wide and indicates the address of the next instruction to be executed.
2.1.8 Flag Register (FLG)
FLG is a 16-bit register indicating the CPU state.
2.1.8.1 Carry Flag (C)
The C flag indicates whether or not carry or borrow has been generated after executing an instruction.
2.1.8.2 Debug Flag (D)
The D flag is for debugging only. Set it to 0.
2.1.8.3 Zero Flag (Z)
The Z flag becomes 1 when an arithmetic operation results in 0; otherwise becomes 0.
2.1.8.4 Sign Flag (S)
The S flag becomes 1 when an arithmetic operation results in a negative value; otherwise becomes 0.
2.1.8.5 Register Bank Select Flag (B)
Register bank 0 is selected when the B flag is set to 0. Register bank 1 is selected when this flag is set to 1.
2.1.8.6 Overflow Flag (O)
The O flag becomes 1 when an arithmetic operation results in an overflow; otherwise becomes 0.
Rev.1.00 Jul 15, 2007 Page 19 of 352
REJ09B0385-0100