SH7760 Datasheet, PDF (87/1345 Pages) Renesas Technology Corp – SuperHTM RISC engine

• H'FC00 0000 to H'FFFF FFFF
Access to area H'FC00 0000 to 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 addresses to which registers are not mapped in either area. The operation of
an access to an address with no register mapped 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.
2.4 Data Formats
2.4.1 Data Format in Registers
Register operands are always longwords (32 bits). When a memory operand is only a byte (8 bits)
or a word (16 bits), it is sign-extended into a longword when loaded into a register.
31
0
Longword
2.4.2 Data Formats in Memory
Memory data formats are classified into bytes, words, and longwords. Memory can be accessed in
an 8-bit byte, 16-bit word, or 32-bit longword form. A memory operand less than 32 bits in length
is sign-extended before being loaded into a register.
A word operand must be accessed starting from a word boundary (even address of a 2-byte unit:
address 2n), and a longword operand starting from a longword boundary (even address of a 4-byte
unit: address 4n). An address error will result if this rule is not observed. A byte operand can be
accessed from any address.
Big endian or little endian byte order can be selected for the data format. The endian should be set
with the MD5 external pin after a power-on reset. Big endian is selected when the MD5 pin is low,
and little endian when high. The endian cannot be changed dynamically. Bit positions are
numbered left to right from most-significant to least-significant. Thus, in a 32-bit longword, the
leftmost bit, bit 31, is the most significant bit and the rightmost bit, bit 0, is the least significant
bit.
The data format in memory is shown in figure 2.4.
Rev. 0.1, 02/03, page 37 of 1294