SH7751 datasheet(86/1105 Pages) RENESAS

86 / 1105 page

Rev. 3.0, 04/02, page 46 of 1064

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 data 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 data.

2.3

Memory-Mapped Registers

Appendix A 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'FC00 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.

SH7751 Datasheet(PDF) 86 Page - Renesas Technology Corp