D12320VF25V Datasheet, PDF (69/1146 Pages) Renesas Technology Corp – Old Company Name in Catalogs and Other Documents

Section 2 CPU
2.4.2 General Registers
The CPU has eight 32-bit general registers. These general registers are all functionally alike and
can be used as both address registers and data registers. When a general register is used as a data
register, it can be accessed as a 32-bit, 16-bit, or 8-bit register. When the general registers are used
as 32-bit registers or address registers, they are designated by the letters ER (ER0 to ER7).
The ER registers divide into 16-bit general registers designated by the letters E (E0 to E7) and R
(R0 to R7). These registers are functionally equivalent, providing a maximum sixteen 16-bit
registers. The E registers (E0 to E7) are also referred to as extended registers.
The R registers divide into 8-bit general registers designated by the letters RH (R0H to R7H) and
RL (R0L to R7L). These registers are functionally equivalent, providing a maximum sixteen 8-bit
registers.
Figure 2.5 illustrates the usage of the general registers. The usage of each register can be selected
independently.
• Address registers
• 32-bit registers
• 16-bit registers
• 8-bit registers
ER registers
(ER0 to ER7)
E registers (extended registers)
(E0 to E7)
R registers
(R0 to R7)
RH registers
(R0H to R7H)
RL registers
(R0L to R7L)
Figure 2.5 Usage of General Registers
General register ER7 has the function of stack pointer (SP) in addition to its general-register
function, and is used implicitly in exception handling and subroutine calls. Figure 2.6 shows the
stack.
Rev.7.00 Feb. 14, 2007 page 35 of 1108
REJ09B0089-0700