Routines
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EA8D: Print Character
Used by the routines at InputLine, InputLine_Redraw, ClipAndPrintCharacter and SubmitInputLine.
Plots one character glyph into the display file. Callers set up PrintState first.
PrintCharacter EA8D PUSH AF Stash the flags, counters, screen pointer and glyph pointer on the stack.
EA8E PUSH BC
EA8F PUSH DE
EA90 PUSH HL
Pick the plot opcode written into PrintCharacter_PlotOpcode: AE (XOR (HL)) or B6 (OR (HL)) from bit 2 of the flags.
EA91 LD A,($5BF6) Fetch *PrintState_Flags and test bit 2.
EA94 BIT 2,A
EA96 LD A,$AE Prefer AE (XOR) unless bit 2 was set.
EA98 JR Z,PrintCharacter_SetPlotOpcode
EA9A LD A,$B6 A=B6 (OR).
PrintCharacter_SetPlotOpcode EA9C LD ($EAF1),A Patch that opcode into PrintCharacter_PlotOpcode.
Point HL at the 8-byte glyph. Codes below 8F use CHARS; 90 and above were meant to index UDG, but the unconditional jump at PrintCharacter_ForceChars always takes the CHARS path.
EA9F LD A,($5BF9) Fetch *PrintState_Character and compare it with 8F.
EAA2 CP $8F
PrintCharacter_ForceChars EAA4 JR PrintCharacter_CharsGlyph Always take the CHARS path at PrintCharacter_CharsGlyph.
Unreachable UDG path (left in the binary after PrintCharacter_ForceChars).
EAA6 JR C,PrintCharacter_CharsGlyph Scale the UDG index and point HL at UDG.
EAA8 SUB $90
EAAA ADD A,A
EAAB ADD A,A
EAAC ADD A,A
EAAD LD E,A
EAAE LD D,$00
EAB0 LD HL,($5C7B)
EAB3 ADD HL,DE
EAB4 JR PrintCharacter_ScreenAddress Jump to PrintCharacter_ScreenAddress.
PrintCharacter_CharsGlyph EAB6 LD DE,($5C36) Point HL at glyph *PrintState_Character in CHARS.
EABA LD L,A
EABB LD H,$00
EABD ADD HL,HL
EABE ADD HL,HL
EABF ADD HL,HL
EAC0 ADD HL,DE
Convert row/column at PrintState_Column into a display-file address in DE.
PrintCharacter_ScreenAddress EAC1 LD DE,$4000 DE=4000.
EAC4 LD BC,($5BF7) BC=*PrintState_Column.
EAC8 LD A,C Jump to PrintCharacter_Exit if the column is out of range.
EAC9 CP $20
EACB JR NC,PrintCharacter_Exit
EACD LD A,B Jump to PrintCharacter_Exit if the row is out of range.
EACE CP $18
EAD0 JR NC,PrintCharacter_Exit
PrintCharacter_RowThirds EAD2 CP $08 Jump to PrintCharacter_ColumnOffset if this row is already in the current third.
EAD4 JR C,PrintCharacter_ColumnOffset
EAD6 SUB $08 Move D down one screen third and try again.
EAD8 PUSH AF
EAD9 LD A,D
EADA ADD A,$08
EADC LD D,A
EADD POP AF
EADE JR PrintCharacter_RowThirds
PrintCharacter_ColumnOffset EAE0 ADD A,A Fold the row remainder and column into E.
EAE1 ADD A,A
EAE2 ADD A,A
EAE3 ADD A,A
EAE4 ADD A,A
EAE5 ADD A,C
EAE6 LD E,A
Copy or XOR the 8 glyph rows into the display file.
EAE7 LD A,($5BF6) Jump to PrintCharacter_CopyLoop if bit 0 of *PrintState_Flags clears XOR mode.
EAEA AND $01
EAEC JR Z,PrintCharacter_CopyLoop
EAEE LD B,$08 B=08.
PrintCharacter_XorLoop EAF0 LD A,(DE) Plot one glyph row with the patched XOR/OR at PrintCharacter_PlotOpcode and move down a pixel line.
PrintCharacter_PlotOpcode EAF1 XOR (HL)
EAF2 LD (DE),A
EAF3 INC HL
EAF4 INC D
EAF5 DJNZ PrintCharacter_XorLoop
EAF7 JR PrintCharacter_Attributes Jump to PrintCharacter_Attributes.
PrintCharacter_CopyLoop EAF9 LD B,$08 B=08.
PrintCharacter_CopyLoop_Body EAFB LD A,(HL) Copy one glyph row into the display file and move down a pixel line.
EAFC LD (DE),A
EAFD INC HL
EAFE INC D
EAFF DJNZ PrintCharacter_CopyLoop_Body
Unless bit 1 of the flags is set, write the attribute from PrintState into the matching attribute-file cell.
PrintCharacter_Attributes EB01 LD A,($5BF6) Jump to PrintCharacter_AdvanceCursor if bit 1 of *PrintState_Flags skips attributes.
EB04 AND $02
EB06 JR NZ,PrintCharacter_AdvanceCursor
EB08 LD A,($5BF5) Point HL at the attribute-file cell for *PrintState_Column.
EB0B LD C,A
EB0C LD DE,($5BF7)
EB10 LD H,$58
EB12 LD A,D
PrintCharacter_AttrRow EB13 SUB $08 Jump to PrintCharacter_AttrNextThird if another attribute third remains.
EB15 JR NC,PrintCharacter_AttrNextThird
EB17 JR PrintCharacter_AttrColumn Jump to PrintCharacter_AttrColumn.
PrintCharacter_AttrNextThird EB19 INC H Step H to the next attribute third and retry.
EB1A JR PrintCharacter_AttrRow
PrintCharacter_AttrColumn EB1C ADD A,$08 Restore the row remainder and load the column.
EB1E LD B,A
EB1F LD A,E
EB20 JR Z,PrintCharacter_WriteAttr
PrintCharacter_0 EB22 ADD A,$20 Add 20 per remaining row to reach the cell.
EB24 DJNZ PrintCharacter_0
PrintCharacter_WriteAttr EB26 LD L,A Write *PrintState into that attribute-file cell.
EB27 LD (HL),C
Advance the cursor: move to the next column, or wrap to the next row.
PrintCharacter_AdvanceCursor EB28 LD DE,($5BF7) Advance the column; jump to PrintCharacter_StoreCursor if still on this row.
EB2C INC E
EB2D LD A,E
EB2E CP $20
EB30 JR NZ,PrintCharacter_StoreCursor
EB32 LD E,$00 Wrap to column 00 on the next row.
EB34 INC D
PrintCharacter_StoreCursor EB35 LD ($5BF7),DE Store the updated cursor back in *PrintState_Column.
PrintCharacter_Exit EB39 POP HL Restore the glyph pointer, screen pointer, counters and flags from the stack.
EB3A POP DE
EB3B POP BC
EB3C POP AF
EB3D RET Return.
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