Difference between revisions of "SCUMM/V6 opcodes"

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behaviour -> behavior
(→‎wordVarInc: added from website)
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Currently all entries from the reference on the [http://www.scummvm.org/docs/specs/scrp-v6.php main ScummVM website] have been transferred - please proofread and fix formatting where applicable.
=SCUMM V6 opcodes=
=SCUMM V6 opcodes=
The following conventions are used in the encoding descriptions.
The following conventions are used in the encoding descriptions.
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Performs a division operation on the stack. Note the order.
Performs a division operation on the stack. Note the order.


An attempt to divide by zero will cause undefined behaviour, and may cause the interpreter to crash.
An attempt to divide by zero will cause undefined behavior, and may cause the interpreter to crash.


==MM 83 doSentence==
==MM 83 doSentence==
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'''Stack'''
'''Stack'''


''( left , top , right , bottom , colour : -)''
''( left , top , right , bottom , color : -)''


'''Operation'''
'''Operation'''
Draws a solid box on the backbuffer from ( left , top ) to ( right , bottom ) in the colour colour .
Draws a solid box on the backbuffer from ( left , top ) to ( right , bottom ) in the color color .


==dup==
==dup==
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If value is any of arg1 .. argn , bool := 1, otherwise bool := 0
If value is any of arg1 .. argn , bool := 1, otherwise bool := 0


Tests to see if value is equal to any of the passed in arguments. If n is less than the number of entries on the stack, undefined behaviour will result.
Tests to see if value is equal to any of the passed in arguments. If n is less than the number of entries on the stack, undefined behavior will result.


==MM 98 isSoundRunning==
==MM 98 isSoundRunning==
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value := arg[index]
value := arg[index]


Returns the index th argument on the stack. If n is less than the number of entries on the stack or index is out of range, undefined behaviour will result, usually involving the interpreter shutting down.
Returns the index th argument on the stack. If n is less than the number of entries on the stack or index is out of range, undefined behavior will result, usually involving the interpreter shutting down.


==pickOneOfDefault==
==pickOneOfDefault==
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If index is in the range 0.. n , value  :=  arg[index] ; otherwise value  :=  default .
If index is in the range 0.. n , value  :=  arg[index] ; otherwise value  :=  default .


Returns the index th argument on the stack. If index is out of range, default is returned instead. If n is less than the number of entries on the stack, undefined behaviour will result, usually involving the interpreter shutting down.
Returns the index th argument on the stack. If index is out of range, default is returned instead. If n is less than the number of entries on the stack, undefined behavior will result, usually involving the interpreter shutting down.


==MM 84 pickupObject==
==MM 84 pickupObject==
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==writeByteVar==
==writeByteVar==
'''Encoding'''
''42 pointer^8''
'''Stack'''
( ''value'' : -)
'''Operation'''
''* pointer := value''
Writes ''value'' to the variable pointed to by ''pointer''. Note that as ''pointer'' is encoded as a byte, it can only point to word variables in the range 0x0000 to 0x00FF. For a more general form of this instruction, use writeWordVar.


==writeWordVar==
==writeWordVar==
'''Encoding'''
''43 pointer^16''
'''Stack'''
''( value : -)''
'''Operation'''
''* pointer := value''
Writes ''value'' to the variable pointed to by ''pointer''.


==zero==
==zero==
'''Encoding'''
''0D''
'''Stack'''
( ''value''  :  ''bool'' )
'''Operation'''
If ''value'' = 0, set ''bool'' to 1, otherwise set it to 0
Tests the value on the stack to see if it compares to zero.




''All material © 2000-2002 David Given, unless where stated otherwise.''
''All material © 2000-2002 David Given, unless where stated otherwise.''
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