HD64F3670 Datasheet, PDF (53/323 Pages) Renesas Technology Corp – Hitachi Single-Chip Microcomputer

The ADDS, SUBS, INC, and DEC instructions contain immediate data implicitly. Some bit
manipulation instructions contain 3-bit immediate data in the instruction code, specifying a bit
number. The TRAPA instruction contains 2-bit immediate data in its instruction code, specifying a
vector address.
Program-Counter Relative—@(d:8, PC) or @(d:16, PC)
This mode is used in the BSR instruction. An 8-bit or 16-bit displacement contained in the
instruction is sign-extended and added to the 24-bit PC contents to generate a branch address. The
PC value to which the displacement is added is the address of the first byte of the next instruction,
so the possible branching range is –126 to +128 bytes (–63 to +64 words) or –32766 to +32768
bytes (–16383 to +16384 words) from the branch instruction. The resulting value should be an
even number.
Memory Indirect—@@aa:8
This mode can be used by the JMP and JSR instructions. The instruction code contains an 8-bit
absolute address specifying a memory operand. This memory operand contains a branch address.
The memory operand is accessed by longword access. The first byte of the memory operand is
ignored, generating a 24-bit branch address. Figure 2.8 shows how to specify branch address for in
memory indirect mode. The upper bits of the absolute address are all assumed to be 0, so the
address range is 0 to 255 (H'0000 to H'00FF).
Note that the first part of the address range is also the exception vector area.
Specified
by @aa:8
Dummy
Branch address
Figure 2.8 Branch Address Specification in Memory Indirect Mode
2.5.2 Effective Address Calculation
Table 2.12 indicates how effective addresses are calculated in each addressing mode. In this LSI
the upper 8 bits of the effective address are ignored in order to generate a 16-bit effective address.
Rev. 2.0, 03/02, page 29 of 298