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Drawing the screen: SEND_DATA_TO_PPU

[NES version, Common]

Name: SEND_DATA_TO_PPU [Show more] Type: Macro Category: Drawing the screen Summary: Send a specified block of memory to the PPU Deep dive: Drawing vector graphics using NES tiles
The following macro is used to send bytes to the PPU: SEND_DATA_TO_PPU byte_count It sends a block of byte_count bytes from memory to the PPU, starting with the Y-th byte of the data block at address dataForPPU(1 0). It also updates the index in Y to point to the byte after the block that is sent.
Arguments: byte_count The number of bytes to send to the PPU Y The index into dataForPPU(1 0) from which to start sending data
Returns: Y The index in Y is updated to point to the byte after the block that is sent
MACRO SEND_DATA_TO_PPU byte_count FOR I%, 1, byte_count LDA (dataForPPU),Y ; Send the Y-th byte of dataForPPU(1 0) to the PPU STA PPU_DATA INY ; Increment the index in Y ; Repeat the above code so that we run it byte_count ; times, so we send a total of byte_count bytes from ; memory to the PPU NEXT ENDMACRO