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51 lines
2 KiB
Plaintext
51 lines
2 KiB
Plaintext
{{DISPLAYTITLE:_MEMGET}}
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The '''_MEMGET''' statement reads a portion of a memory block at an OFFSET position into a variable, array or user defined type.
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{{PageSyntax}}
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::: '''_MEMGET ''memory_block'', ''byte_position'', ''holding_variable'''''
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* ''memory block'' is a [[_MEM]] variable type memory block name created by [[_MEMNEW]] or the [[_MEM (function)|_MEM]] function.
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* mandatory ''byte_position'' is the ''memory_block.[[OFFSET]]'' memory start position plus any bytes to move into the block.
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* ''holding variable'' is the variable assigned to hold the data. The number of bytes read is determined by the variable [[type]] used.
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''Usage:''
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* The _MEMGET statement is similar to the [[GET]] statement used in files, but the position is required.
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* The memory block name.[[OFFSET]] returns the starting byte position of the block. Add bytes to move into the block.
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* The variable type held in the memory block can determine the next ''byte position'' to read.
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* [[LEN]](variable) can determine the byte size of numerical or user defined variable [[type]]s irregardless of the value held.
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* [[STRING]] values should be of a defined length. Variable length strings can actually move around in memory and not be found.
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''Example:'' Shows how to read the PSET color values from a program's [[SCREEN]] memory to an array.
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{{CodeStart}} '' ''
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{{Cl|SCREEN}} 13
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{{Cl|PSET}} (0, 0), 123
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{{Cl|PSET}} (1, 0), 222 'create screen image
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'here is an array
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{{Cl|DIM}} screen_array(319, 199) {{Cl|AS}} {{Cl|_UNSIGNED}} {{Cl|_BYTE}} 'use screen dimensions from 0
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'here's how we can copy the screen to our array
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{{Cl|DIM}} m {{Cl|AS}} {{Cl|_MEM}}
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m = {{Cl|_MEMIMAGE}} '0 or no handle necessary when accessing the current program screen
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{{Cl|_MEMGET}} m, m.OFFSET, screen_array()
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'here's the proof
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{{Cl|PRINT}} screen_array(0, 0) 'print 123
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{{Cl|PRINT}} screen_array(1, 0) 'print 222
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{{Cl|END}} '' ''
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{{CodeEnd}}
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''See also:''
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* [[_MEMGET (function)]]
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* [[_MEMPUT]]
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* [[_MEM]]
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* [[_MEMIMAGE]]
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* [[_MEMFREE]]
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{{PageNavigation}} |