SH7616 datasheet(57/935 Pages) RENESAS

57 / 935 page

Section 2 CPU

Rev. 2.00 Mar 09, 2006 page 31 of 906

REJ09B0292-0200

Section 2 CPU

2.1

The register set consists of sixteen 32-bit general registers, six 32-bit control registers and ten 32-

bit system registers.

This chip is upwardly compatible with the SH-1, SH-2 on the object code level. For this reason,

several registers have been added to the previous SuperH microcontroller registers. The added

registers are the three control registers: repeat start register (RS), repeat end register (RE), and

modulo register (MOD) and the six system registers: DSP status register (DSR), and A0, A1, X0,

X1, Y0 and Y1 among the DSP data registers.

The general registers are used in the same manner as the SH-1, SH-2 with regard to SuperH

microcontroller-type instructions. With regard to DSP type instructions, they are used as address

and index registers for accessing memory.

2.1.1

General Registers

There are 16 general registers (Rn) numbered R0–R15, which are 32 bits in length. General

registers are used for data processing and address calculation.

With SuperH microcomputer type instructions, R0 is also used as an index register. Several

instructions are limited to use of R0 only. R15 is used as the hardware stack pointer (SP). Saving

and recovering the status register (SR) and program counter (PC) in exception processing is

accomplished by referencing the stack using R15.

With DSP type instructions, eight of the 16 general registers are used for the addressing of X, Y

data memory and data memory (single data) using the I bus.

R4, R5 are used as an X address register (Ax) for X memory accesses, and R8 is used as an X

index register (Ix). R6, R7 are used as a Y address register (Ay) for Y memory accesses, and R9 is

used as a Y index register (Iy). R2, R3, R4, R5 are used as a single data address register (As) for

accessing single data using the I bus, and R8 is used as a single data index register (Is).

DSP type instructions can simultaneously access X and Y data memory. There are two groups of

address pointers for designating X and Y data memory addresses.

Figure 2.1 shows the general registers.

SH7616 Datasheet(PDF) 57 Page - Renesas Technology Corp