Zilog Z80380 Manual de usuario descargar pdf (Pagina 136)

5-102

Z380

™

USER'S MANUAL

DC-8297-03

ZILOG

LDIR

LOAD, INCREMENT AND REPEAT (BYTE)

LDIR

Operation: repeat until (BC=0) begin

(DE) ← (HL)

DE ← DE + 1

HL ← HL + 1

BC(15-0) ← BC(15-0) – 1

end

This instruction is used for block transfers of strings of data. The bytes of data at the location

addressed by the HL register are loaded into memory starting at the location addressed by

the DE register. The number of bytes moved is determined by the contents of the BC register.

If the BC register contains zero when this instruction is executed, 65,536 bytes are

transferred. The effect of incrementing the pointers during the transfer is important if the

source and destination strings overlap with the source string starting at a higher memory

address. Placing the pointers at the lowest address of the strings and incrementing the

pointers ensures that the source string is copied without destroying the overlapping area.

This instruction can be interrupted after each execution of the basic operation. The Program

Counter value of the start of this instruction is saved before the interrupt request is

accepted,so that the instruction can be properly resumed.

Flags: S: Unaffected

Z: Unaffected

H: Cleared

V: Cleared

N: Cleared

C: Unaffected

Addressing Execute

Mode Syntax Instruction Format Time Note

LDIR 11101101 10110000 3+r+w

1 2 ... 131 132 133 134 135 136 137 138 139 140 141 ... 267 268

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Zilog Z80380 Manual de usuario Pagina 136