Routines
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A2BD: Extract Object Attributes
Used by the routines at ProcessObjectDisplay, ProcessObject_Display, SwapObjectDisplayPointers and ProcessDisplayAction.
Packs two attribute nibbles from the object record into A01E and ObjectAttributeValue.
Input
IX Pointer to object data
Extract the first attribute value from bit-packed object data.
ExtractObjectAttributes A2BD LD A,(IX+$05) Read the object attribute.
A2C0 RRCA
A2C1 RRCA
A2C2 RRCA
A2C3 RRCA
A2C4 AND %00001111 Keep the high nibble of the object attribute (now in bits 0-3) as the low half of the display flag.
A2C6 LD C,A Read the character record.
A2C7 LD A,(IX+$07)
A2CA AND %11110000 Take the high nibble of byte 07 of the object data as the high half of the display flag.
A2CC ADD A,C Join the two halves into one byte.
A2CD LD ($A01E),A Record the result in the display flag at A01E.
Extract the second attribute value from bit-packed object data.
A2D0 LD A,(IX+$01) Read the moved marker.
A2D3 RRCA
A2D4 RRCA
A2D5 RRCA
A2D6 RRCA
A2D7 AND %00001111 Keep the high nibble of the moved marker (now in bits 0-3) as the low half of the object attribute value.
A2D9 LD C,A Read the action flags.
A2DA LD A,(IX+$03)
A2DD AND %11110000 Take the high nibble of the action flags (byte 03) as the high half of the object attribute value.
A2DF ADD A,C Join the two halves into one byte.
A2E0 LD ($A01D),A Record the result in the object attribute value at ObjectAttributeValue.
A2E3 RET Return.
View the equivalent code in;
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