HD6417660 RENESAS [Renesas Technology Corp], HD6417660 Datasheet - Page 156

• Manufacturer Part Number: HD6417660
• Description: Renesas 32-Bit RISC Microcomputer
• Manufacturer: RENESAS [Renesas Technology Corp]

3.5.4
Figure 3.9 shows the ALU fixed-point arithmetic operation flow. Table 3.21 shows the variation
of this type of operation and table 3.22 shows the correspondence between each operand and
registers.
Note: The ALU fixed-point arithmetic operations are basically 40-bit operation; 32 bits of the
ALU fixed-point operations are executed between registers. Each source and destination operand
are selected independently from one of the DSP registers. When a register providing guard bits is
specified as an operand, the guard bits are activated for this type of operation. These operations are
executed in the DSP stage, as shown in figure 3.10. The DSP stage is the same stage as the MA
stage in which memory access is performed.
Rev. 1.00, 02/04, page 118 of 804
base precision and 8 bits of the guard-bit parts. So the signed bit is copied to the guard-bit
parts when a register not providing the guard-bit parts is specified as the source operand.
When a register not providing the guard-bit parts is specified as a destination operand, the
lower 32 bits of the operation result are input into the destination register.
ALU Fixed-Point Arithmetic Operations
39
Guard
31
Source 1
Figure 3.9 ALU Fixed-Point Arithmetic Operation Flow
39
Guard
31
0
ALU
39
Guard
Destination
31
Source 2
0
DSR
0
GT Z
N
V DC