HD6417615 Hitachi Semiconductor, HD6417615 Datasheet - Page 105

• Manufacturer Part Number: HD6417615
• Description: Hardware Manual
• Manufacturer: Hitachi Semiconductor

Precautions Concerning the Number of Instruction Execution Cycles: The execution cycles
listed in the tables are minimum values. In practice, the number of execution cycles increases
under such conditions as 1) when the instruction fetch is in contention with a data access, 2) when
the destination register of a load instruction (memory
register) is the same as the register used
by the next instruction, 3) when the branch destination address of a branch instruction is a 4n + 2
address.
CPU Instructions That Support DSP Functions: A number of system control instructions have
been added to the CPU core instructions to support DSP functions. The RS, RE and MOD
registers have been added to support repeat control and modulo addressing, and the repeat counter
(RC) has been added to the status register (SR). The LDC and STC instructions have been added
in order to access the aforementioned. The LDS and STS instructions have been added in order to
access the DSP registers DSR, A0, X0, X1, Y0 and Y1.
The SETRC instruction has been added to set the repeat counter (RC, bits 27 to 16) and repeat
flags (RF1, RF0, bits 3 and 2) of the SR register. When the SETRC instruction operand is
immediate, the 8-bit immediate data is stored in bits 23 to 16 of the SR register and bits 27 to 24
are cleared to 0. When the operand is a register, bits 11 to 0 (12 bits) of the register are stored in
bits 27 to 16 of the SR register. Additionally, the status of 1 instruction repeat (00), 2 instruction
repeat (01), 3 instruction repeat (11) or 4 instruction or greater repeat (10) is set from the RS and
RE set values.
In addition to the LDC instruction, the LDRS and LDRE instructions have been added for
establishing the repeat start and repeat end addresses in the RS and RE registers.
The added instructions are listed in table 2.26.
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