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Drawing the screen: FILL_MEMORY

[NES version, Common]

Name: FILL_MEMORY [Show more] Type: Macro Category: Drawing the screen Summary: Fill memory with the specified number of bytes
Context: See this macro in context in the source code References: This macro is used as follows: * ClearMemory uses FILL_MEMORY * FillMemory uses FILL_MEMORY * FillMemory32Bytes uses FILL_MEMORY

The following macro is used to fill a block of memory with the same value: FILL_MEMORY byte_count It writes the value A into byte_count bytes, starting at the Y-th byte of the memory block at address clearAddress(1 0). It also updates the index in Y to point to the byte after the block that is filled.
Arguments: byte_count The number of bytes to fill clearAddress(1 0) The base address of the block of memory to fill Y The index into clearAddress(1 0) from which to fill A The value to fill
Returns: Y The index in Y is updated to point to the byte after the filled block
MACRO FILL_MEMORY byte_count FOR I%, 1, byte_count STA (clearAddress),Y ; Write A to the Y-th byte of clearAddress(1 0) INY ; Increment the index in Y ; Repeat the above code so that we run it byte_count ; times, so write a total of byte_count bytes into ; memory NEXT ENDMACRO