HD6417616 RENESAS [Renesas Technology Corp], HD6417616 Datasheet - Page 66

• Manufacturer Part Number: HD6417616
• Description: 32-Bit RISC Microcomputer SuperH™ RISC engine Family/SH7600 Series
• Manufacturer: RENESAS [Renesas Technology Corp]

Section 2 CPU
2.1.5
DSP unit data operations are fundamentally performed as 32-bit, but these operations are always
executed with a 40-bit length including the 8-bit guard section. When the guard bit section does
not match the value of the 32-bit section MSB, the operation result is treated as an overflow. In
this case, the N bit indicates the correct status of the operation result regardless of the existence or
not of an overflow. This is so even if the destination operand is a 32-bit length register. The 8-bit
section guard bits are always presupposed and each status flag is updated.
When place overflows occur so that the correct result cannot be displayed even when the guard
bits are used, the N flag cannot indicate the correct status.
2.1.6
Table 2.3 lists the values of the registers after reset.
Table 2.3
Rev. 2.00 Mar 09, 2006 page 40 of 906
REJ09B0292-0200
Classification
General registers
Control registers
System registers
DSP registers
Notes on Guard Bits and Overflow Treatment
Initial Values of Registers
Initial Values of Registers
Register
R0–R14
R15 (SP)
SR
RS
RE
GBR
VBR
MOD
MACH, MACL, PR
PC
A0, A0G, A1, A1G, M0,
M1, X0, X1, Y0, Y1
DSR
Undefined
Bits I3–I0 are 1111 (H'F), the reserved bits, RC, DMY,
Initial Value
Value of the SP in the vector address table
and DMX are 0, and other bits are undefined
Undefined
Undefined
H'00000000
Undefined
Undefined
Value of the PC in the vector address table
Undefined
H'00000000