When an FPU operation instruction is executed, the FPU exception cause field is cleared to
zero first. When the next FPU exception is occured, the corresponding bits in the FPU
exception cause field and FPU exception flag field are set to 1. The FPU exception flag field
holds the status of the exception generated after the field was last cleared.
•
•
RM: Rounding mode
RM = 00: Round to Nearest
RM = 01: Round to Zero
RM = 10: Reserved
RM = 11: Reserved
Bits 22 to 31: Reserved
Floating-point communication register, FPUL (32 bits, initial value undefined): Data transfer
between FPU registers and CPU registers is carried out via the FPUL register.
Programming Note: When SZ = 1 and big endian mode is selected, FMOV can be used for
double-precision floating-point load or store operations. In little endian mode, two 32-bit data size
moves must be executed, with SZ = 0, to load or store a double-precision floating-point number.
2.3
Memory-Mapped Registers
Appendix A, Address List shows the control registers mapped to memory. The control registers
are double-mapped to the following two memory areas. All registers have two addresses.
H'1C00 0000–H'1FFF FFFF
H'FC00 0000–H'FFFF FFFF
These two areas are used as follows.
•
H'1C00 0000–H'1FFF FFFF
This area must be accessed using the address translation function of the MMU. Setting the
page number of this area to the corresponding filed of the TLB enables access to a memory-
mapped register. Accessing this area without using the address translation function of the
MMU is not guaranteed.
•
H'FC00 0000–H'FFFF FFFF
Access to area H'FF00 0000–H'FFFF FFFF in user mode will cause an address error. Memory-
mapped registers can be referenced in user mode by means of access that involves address
translation.
Note: Do not access undefined locations in either area The operation of an access to an
undefined location is undefined. Also, memory-mapped registers must be accessed using a
fixed data size. The operation of an access using an invalid data size is undefined.
Rev. 6.0, 07/02, page 52 of 986
RENESAS [ RENESAS TECHNOLOGY CORP ]
