Routines
Prev: BDAE Up: Map Next: BE85
BE5B: Draw Aligned Columns
Draws the columns of a sprite which is not shifted or flipped. There is a piece of code for each of up to five columns, and the code for the width of the sprite is where the jump at SpriteJumpOpcode starts. Each piece takes the mask and the pixels for one byte of the row from the sprite data on the stack, wipes the screen where the mask is and puts the pixels in. The buffer address is in BC.
DrawAlignedColumns BE5B POP DE Fetch the mask into E and the pixels into D.
BE5C LD A,(BC) Clear the screen bits under the mask.
BE5D CPL
BE5E OR E
BE5F CPL
BE60 OR D Add the pixels.
BE61 LD (BC),A Store the byte and move on to the next.
BE62 INC BC
BE63 POP DE Fetch the mask into E and the pixels into D.
BE64 LD A,(BC) Clear the screen bits under the mask.
BE65 CPL
BE66 OR E
BE67 CPL
BE68 OR D Add the pixels.
BE69 LD (BC),A Store the byte and move on to the next.
BE6A INC BC
BE6B POP DE Fetch the mask into E and the pixels into D.
BE6C LD A,(BC) Clear the screen bits under the mask.
BE6D CPL
BE6E OR E
BE6F CPL
BE70 OR D Add the pixels.
BE71 LD (BC),A Store the byte and move on to the next.
BE72 INC BC
BE73 POP DE Fetch the mask into E and the pixels into D.
BE74 LD A,(BC) Clear the screen bits under the mask.
BE75 CPL
BE76 OR E
BE77 CPL
BE78 OR D Add the pixels.
BE79 LD (BC),A Store the byte and move on to the next.
BE7A INC BC
BE7B POP DE Fetch the mask into E and the pixels into D.
BE7C LD A,(BC) Clear the screen bits under the mask.
BE7D CPL
BE7E OR E
BE7F CPL
BE80 OR D Add the pixels.
BE81 LD (BC),A Store the byte.
Finish the row.
BE82 JP FinishSpriteRow Jump to FinishSpriteRow.
View the equivalent code in;
Prev: BDAE Up: Map Next: BE85