HD6417660 RENESAS [Renesas Technology Corp], HD6417660 Datasheet - Page 136

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

instruction, the specified condition does not affect the data transfer operations. For details, refer to
section 3.5, DSP Data Operation Instructions.
Double data transfer instructions can access only the X memory or Y memory and cannot access
other memory space. The X bus and Y bus are 16 bits and support 64-kbyte address spaces
corresponding to address areas H'A5000000 to H'A500FFFF and H'A5010000 to H'A501FFFF,
respectively. Because these areas are included in the P2/Uxy area, they are not affected by the
cache and address translation unit.
Single data transfer instructions: The instruction formats of single data transfer instructions are
shown in table 3.13. The single data transfer instructions access any memory location. All DSP
registers* other than the DSR can be specified as source and destination operands. Guard bit
registers A0G and A1G can also be specified as two independent registers. Because the single
data transfer instructions use the L bus (LAB and LDB), these instructions can access any virtual
space handled by the CPU. If these instructions access the cacheable area while the cache is
enabled, the area accessed by these instructions are cached. The X memory and Y memory are
mapped to the virtual address space and can also be accessed by the single data transfer
instructions. In this case, bus conflict may occur between data transfer and instruction fetch
because the CPU also uses the L bus for instruction fetches.
The single data transfer instructions can handle both word and longword data. In word data
transfer, only the upper word of the operand register is valid. In word data load, word data is
loaded into the upper word of the destination registers and the lower word of the destination is
automatically cleared to 0. If the guard bits are supported, the sign bit is extended before storage.
In longword data load, longword data is loaded into the upper and lower word of the destination
register. If the guard bits are supported, the sign bit is extended before storage. When the guard
register is stored, the sign bit is extended to the upper 24 bits of the LDB and are loaded onto the
LDB bus.
Notes: * Because the DSR register is defined as the system register, it can be accessed by the
System control instructions: The DSR, A0, X0, X1, Y0, and Y1 registers in the DSP unit can
also be used as the CPU system registers. Accordingly, data transfer operations between these
DSP system registers and general registers or memory can be executed by the STS and LDS
instructions. These DSP system registers can be treated as the CPU system register such as PR,
MACL and MACH and can use the same addressing modes.
Rev. 1.00, 02/04, page 98 of 804
1. Any data transfer instruction is executed at the MA stage of the pipeline.
2. Any data transfer instruction does not modify the condition code bits of the DSR
LDS or STS instruction.
register.