Routines
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29004: Print Character
Used by the routines at DisplayPlayerLives, Score_1UP and PrintString.
Input
A ASCII value to print
HL Screen address
PrintScreen 29004 PUSH BC Stash BC, DE and HL on the stack.
29005 PUSH DE
29006 PUSH HL
29007 LD L,A Create an offset in HL.
29008 LD H,0
29010 ADD HL,HL HL=HL * 8.
29011 ADD HL,HL
29012 ADD HL,HL
29013 LD DE,(23606) DE=CHARS.
29017 ADD HL,DE DE=HL + 15360. For examples of usage;
Letter ASCII Value * 8 (offset) CHARS + offset
"U" 85 680 16040
"L" 76 608 15968
"T" 84 672 16032
"I" 73 584 15944
"M" 77 616 15976
"A" 65 520 15880
"T" 84 672 16032
"E" 69 552 15912
29018 EX DE,HL
Print the character to the screen.
29019 POP HL Restore HL, containing the screen buffer location, from the stack.
This entry point is used by the routine at DisplayPlayerLives.
PrintScreen_0 29020 LD B,8 B=8 (8 rows of pixels).
This entry point is used by the routine at 30317.
PrintScreen_Loop 29022 LD A,(DE) Copy a byte from the font data to the screen buffer.
29023 LD (HL),A
29024 INC DE Increment the font data by one.
29025 INC H Move onto the next pixel line.
29026 DJNZ PrintScreen_Loop Decrease counter by one and loop back to PrintScreen_Loop until counter is zero.
29028 POP DE Restore DE and BC from the stack.
29029 POP BC
Reset HL and move to the next column, ready to print the next character.
29030 LD A,H H=H - 8 (reset the display line).
29031 SUB 8
29033 LD H,A
29034 INC L Increment screen column by one.
29035 RET Return.
View the equivalent code in;
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