Epson CMOS 32-Bit Single Chip Microcomputer S1C33L03 Uživatelský manuál stáhnout pdf (Strana 32)

5 INSTRUCTION SET

EPSON

S1C33 FAMILY C33 PE CORE MANUAL

5.5.5 Register Indirect Addressing with Displacement

In this mode, memory is accessed beginning with the address that is derived by adding a specified immediate

(displacement) to the register content. Unless

ext instructions are used, this addressing mode can only be used for

load instructions that have

[%sp+imm6] as the operand.

Examples: ld.b %r0,[%sp+0x10]

The byte data at the address derived by adding 0x10 to the content of the current SP is loaded into the

R0 register. For byte data transfers, the 6-bit immediate is added directly as the displacement.

ld.h %r0,[%sp+0x10]

The halfword data at the address derived by adding 0x20 to the content of the current SP is loaded into

the R0 register. For halfword data transfers, because halfword boundary addresses are accessed, twice

the 6-bit immediate (least significant bit always 0) is the displacement.

ld.w %r0,[%sp+0x10]

The word data at the address derived by adding 0x40 to the content of the current SP is loaded into the

R0 register. For word data transfers, because word boundary addresses are accessed, four times the 6-bit

immediate (2 low-order bits always 0) is the displacement.

If ext instructions described in Section 5.6 are used, ordinary register indirect addressing (

[%rb]) becomes a

special addressing mode in which the immediate specified by the

ext instruction constitutes the displacement.

Example: ext imm13

ld.b %rd,[%rb] The memory address to be accessed is “%rb+imm13.”

5.5.6 Signed PC Relative Addressing

This addressing mode is used for branch instructions that have a signed 8-bit immediate (sign8) in their operand.

When these instructions are executed, the program branches to the address derived by adding twice the

sign8 value

(halfword boundary) to the current PC.

Example: PC + 0

jrne 0x04 The program branches to the PC + 8 address when the jrne branch

: : condition holds true.

: : (PC + 0) + 0x04

∗ 2 → PC + 8

PC + 8

1 2 ... 27 28 29 30 31 32 33 34 35 36 37 ... 180 181

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Epson CMOS 32-Bit Single Chip Microcomputer S1C33L03 Uživatelský manuál Strana 32