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https://github.com/QB64-Phoenix-Edition/QB64pe.git
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6e01fc8dce
Added new _STRCMP and _STRICMP commands for quick string comparisons. Cleaned up QB64 to finish removing the QUI (quick user insert) code and folders. Altered UCASE and LCASE routines to be faster in some situations for us.
71 lines
2.7 KiB
Plaintext
71 lines
2.7 KiB
Plaintext
The '''_MEMCOPY''' statement copies a block of bytes from one memory offset TO another offset in memory.
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{{PageSyntax}}
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:: '''_MEMCOPY ''source_block'', ''source_block.OFFSET'', ''source_block.SIZE'' [[TO]] ''dest_block'', ''dest_block.OFFSET'''''
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{{Parameters}}
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* ''source block'' is the source memory block name created AS [[_MEM]].
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* ''source block.OFFSET'' is the dot [[_OFFSET]] within the source memory block to read from.
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* ''source block.SIZE'' is the total number of bytes to transfer based on actual size.
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* ''dest block'' is the destination [[_MEM]] memory block name to transfer data to.
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* ''dest block.OFFSET'' is the dot [[_OFFSET]] within the dest [[_MEM]] memory block to write to.
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''Usage:''
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* The dot OFFSET is the memory block's start location in memory. Add bytes to place data further into the block.
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* The dot SIZE is the total byte size of the memory block to transfer. You can transfer all or a portion of the data bytes.
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* The memory block regions may overlap.
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* '''Always free memory blocks after values have been transferred to variables and are no longer required!'''
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''Example:'' Swapping data from one [[STRING]] variable to another. Fixed length strings are recommended for speed.
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{{CodeStart}} '' ''
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{{Cl|DIM}} m {{Cl|AS}} {{Cl|_MEM}}
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{{Cl|DIM}} n {{Cl|AS}} {{Cl|_MEM}}
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m = {{Cl|_MEMNEW}}(10)
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n = {{Cl|_MEMNEW}}(100)
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{{Cl|_MEMPUT}} m, m.OFFSET, "1234567890"
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s$ = {{Cl|SPACE$}}(10) 'to load into a variable length string set its length first
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{{Cl|_MEMGET}} m, m.OFFSET, s$
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{{Cl|PRINT}} "in:[" + s$ + "]"
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{{Cl|_MEMCOPY}} m, m.OFFSET, m.SIZE {{Cl|TO}} n, n.OFFSET 'put m into n
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b$ = {{Cl|SPACE$}}(10)
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{{Cl|_MEMGET}} n, n.OFFSET, b$
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{{Cl|PRINT}} "out:[" + b$ + "]"
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{{Cl|_MEMFREE}} m: {{Cl|_MEMFREE}} n 'always clear the memory when done '' ''
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{{CodeEnd}}
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''Snippet:'' Instead of copying each array element, one at a time in nested [[FOR...NEXT|FOR]] loops, _MEMCOPY does it in one statement instantly.
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{{TextStart}} '' ''
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'copy array a to array b one index at a time:
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{{Cb|FOR...NEXT|FOR}} i1 = 0 {{Cb|TO}} 100
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{{Cb|FOR...NEXT|FOR}} i2 = 0 {{Cb|TO}} 100
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b(i1, i2) = a(i1, i2)
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{{Cb|NEXT}}
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{{Cb|NEXT}}
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'copy array a to array b in memory instantly:
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{{Cb|DIM}} ma {{Cl|AS}} {{Cb|_MEM}}: ma = {{Cb|_MEM (function)|_MEM}}(a()) 'place array data into blocks
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{{Cb|DIM}} mb {{Cl|AS}} {{Cb|_MEM}}: mb = {{Cb|_MEM (function)|_MEM}}(b())
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{{Cb|_MEMCOPY}} ma, ma.OFFSET, ma.SIZE {{Cb|TO}} mb, mb.OFFSET
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{{Cb|_MEMFREE}} ma: {{Cb|_MEMFREE}} mb 'clear the memory when done '' ''
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{{TextEnd}}
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''See also:''
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* [[_MEM]], [[_MEM (function)]]
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* [[_MEMNEW]], [[_MEMGET (function)]]
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* [[_MEMIMAGE]], [[_MEMELEMENT]]
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* [[_MEMGET]], [[_MEMPUT]]
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* [[_MEMFILL]], [[_MEMFREE]]
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{{PageNavigation}} |