Datasheet

V850ES/JG3 CHAPTER 3 CPU FUNCTION
R01UH0015EJ0300 Rev.3.00 Page 36 of 870
Sep 30, 2010
3.4.2 Wraparound of CPU address space
(1) Program space
Of the 32 bits of the PC (program counter), the higher 6 bits are fixed to 0 and only the lower 26 bits are valid. The
higher 6 bits ignore a carry or borrow from bit 25 to 26 during branch address calculation.
Therefore, the highest address of the program space, 03FFFFFFH, and the lowest address, 00000000H, are
contiguous addresses. That the highest address and the lowest address of the program space are contiguous in
this way is called wraparound.
Caution Because the 4 KB area of addresses 03FFF000H to 03FFFFFFH is an on-chip peripheral I/O area,
instructions cannot be fetched from this area. Therefore, do not execute an operation in which
the result of a branch address calculation affects this area.
Program space
Program space
(+) direction (−) direction
00000001H
00000000H
03FFFFFFH
03FFFFFEH
(2) Data space
The result of an operand address calculation operation that exceeds 32 bits is ignored.
Therefore, the highest address of the data space, FFFFFFFFH, and the lowest address, 00000000H, are
contiguous, and wraparound occurs at the boundary of these addresses.
Data space
Data space
(+) direction (−) direction
00000001H
00000000H
FFFFFFFFH
FFFFFFFEH