Zilog Z80380 Bedienungsanleitung PDF herunterladen (Seite 140)

5-106

Z380

™

USER'S MANUAL

DC-8297-03

ZILOG

MULTW

MULTIPLY (WORD)

MULTW [HL,]src src = R, RX, IM, X

Operation: HL(31-0) ← HL(15-0) x src(15-0)

The contents of the HL register are multiplied by the source operand and the product is

stored in the HL register. The contents of the source are unaffected. Both operands are

treated as signed, two’s complement integers.

The initial contents of the HL register are overwritten by the result. The Carry flag is set to

indicate that the upper word of the HL register is required to represent the result; if the Carry

flag is cleared, the product can be correctly represented in 16 bits and the upper word of

the HL register merely holds sign-extension data.

Flags: S: Set if the result is negative; cleared otherwise

Z: Set if the result is zero; cleared otherwise

H: Unaffected

V: Cleared

N: Unaffected

C: Set if the product is less than –32768 or greater than or equal to 32768; cleared

otherwise

Addressing Execute

Mode Syntax Instruction Format Time Note

R: MULTW [HL,]R 11101101 11001011 100100rr 10

RX: MULTW [HL,]RX 11101101 11001011 1001010y 10

IM: MULTW [HL,]nn 11101101 11001011 10010111 -n(low)- -n(high) 10

X: MULTW [HL,](XY+d) 11y11101 11001011 ——d— 10010010 12+r I

Field Encodings: rr: 00 for BC, 01 for DE, 11 for HL

y: 0 for IX, 1 for IY

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Zilog Z80380 Bedienungsanleitung Seite 140