Routines
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52280: Draw Line Pair
Used by the routine at DrawFrame.
Draws a horizontal line of solid bytes at each of two screen addresses and moves both addresses up one pixel row. The length of the lines is in offset 16 of the table.
Input
DE Second screen address
HL First screen address
IX Address of the table (FrameParameters)
Output
DE Second screen address, one row up
HL First screen address, one row up
DrawLinePair 52280 LD B,(IX+16) The length of the rules, in bytes.
52283 PUSH HL Keep the address of the first rule.
52284 PUSH DE Keep the address of the second rule.
DrawLinePair_Loop 52285 LD (HL),255 Plot a solid byte on the first rule.
52287 LD A,255 A solid byte is 255.
52289 LD (DE),A Plot it on the second rule.
52290 INC DE Move along the second rule.
52291 INC HL Move along the first rule.
52292 DJNZ DrawLinePair_Loop Repeat for the whole length of the rules.
52294 POP DE Back to the start of the second rule.
52295 POP HL Back to the start of the first rule.
52296 DEC D Move the second rule up one pixel row.
52297 DEC H Move the first rule up one pixel row.
52298 RET Return.
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