SH7708 Datasheet, PDF (36/633 Pages) Renesas Technology Corp – SuperH™ RISC engine

31
0 ^{Saved Status Register (SSR)}
SSR
Stores current SR value at time of exception to indicate processor
status in return to instruction stream from exception handler.
Its contents are undefined after a reset.
31
0 Saved Program Counter (SPC)
SPC
Stores current PC value at time of exception to indicate return
address at completion of exception handling.
Its contents are undefined after a reset.
31
0 Global Base Register (GBR)
GBR
Stores base address of GBR-indirect addressing mode.
The GBR-indirect addressing mode is used for on-chip supporting
module register area data transfers and logic operations.
The GBR register can also be accessed in user mode.
Its contents are undefined after a reset.
31
0 Vector Base Register (VBR)
VBR
Stores base address of exception handling vector area.
Initialized to H'0000000 by a reset.
31 30 29 28 27
10 9 8 7
3 1 0 _Status
0 MD RB BL 0––––––––––––––––––––––––––––0 M Q I3 I2 I1 I0 0 0 S T ^register
(SR)
MD: Processor operation mode bit: Indicates the processor operation mode as follows:
MD =1: Privileged mode; MD = 0: User mode
MD is set to 1 on generation of an exception or interrupt , and is initialized to 1 by a reset.
RB: Register bank bit: Determines the bank of general registers R0–R7 used in processing mode.
RB = 1: R0_BANK1–R7_BANK1 and R8–R15 are general registers, and R0_BANK0–
R7_BANK0 can be accessed by LDC/STC instructions.
RB = 0: R0_BANK0–R7_BANK0 and R8–R15 are general registers, and R0_BANK1–
R7_BANK1 can be accessed by LDC/STC instructions.
RB is set to 1 on generation of an exception or interrupt , and is initialized to 1 by a reset.
BL: Block bit
BL = 1: Exceptions and interrupts are suppressed. See section 4, Exception
Handling, for details.
BL = 0: Exceptions and interrupts are accepted.
BL is set to 1 on generation of an exception or interrupt , and is initialized to 1 by a reset.
M and Q bits: Used by the DIV0S/U and DIV1 instructions.
I3–I0 bits: Interrupt mask bits: 4-bit field indicating the interrupt request mask level.
I3–I0 do not change to the interrupt acceptance level when an interrupt is generated.
Initialized to B'1111 by a reset.
S bit: Used by the MAC instruction.
T bit: Used by the MOVT, CMP/cond, TAS, TST, BT, BF, SETT, CLRT, and DT instructions to
indicate true (1) or false (0).
Used by the ADDV/C, SUBV/C, DIV0U/S, DIV1, NEGC, SHAR/L, SHLR/L, ROTR/L, and
ROTCR/L instructions to indicate a carry, borrow, overflow, or underflow.
0 bits: These bits always read 0, and the write value should always be 0.
Note: The M, Q, S, and T bits can be set or cleared by special instructions in user mode.
Their values are undefined after a reset. All other bits can be read or written in privileged mode.
Figure 2.5 Register Set Overview, Control Registers
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