Routines
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$0ECF: Make a teacher give lines to the closest main kid
This corresponds to $78AA in the ZX Spectrum version.
Used by the routine at $2A43. Makes a teacher who has been knocked over give lines to the closest main kid (if any).
$0ECF JSR $0BAC Compute the coordinate ranges within which the teacher can see.
$0ED2 LDA #$FF $79 will hold the distance from the teacher to the closest main kid. Initialise it to $FF.
$0ED4 STA $79
First we check whether ERIC is in range.
$0ED6 LDA #$14 Character number $14 is ERIC.
$0ED8 STA $07 Store this potential target character number at $07.
$0EDA JSR $0D67 Is ERIC close to the teacher?
$0EDD BCC $0F0B Branch if not to check EINSTEIN.
$0EDF LDA #$78 Prepare to address ERIC's character buffer at $8C60.
$0EE1 CLC
$0EE2 ADC $07
$0EE4 STA $4F
$0EE6 LDA #$60
$0EE8 STA $4E
$0EEA LDY #$01 Pick up ERIC's x-coordinate from his character buffer and store it at $0B.
$0EEC LDA ($4E),Y
$0EEE STA $0B
$0EF0 CMP $FC Is it less than the teacher's x-coordinate?
$0EF2 BCC $0EFA Branch if so.
$0EF4 SEC Now A holds the difference between the teacher's and ERIC's x-coordinates.
$0EF5 SBC $FC
$0EF7 JMP $0EFF Jump forward.
$0EFA LDA $FC Pick up the teacher's x-coordinate from $FC.
$0EFC SEC Now A holds the difference between the teacher's and ERIC's x-coordinates.
$0EFD SBC $0B
$0EFF STA $7A Store this x-coordinate difference at $7A.
$0F01 CMP $79 Is it greater than any x-coordinate difference already calculated?
$0F03 BCS $0F0B Branch if so (this branch is never made).
$0F05 STA $79 Otherwise store this new minimum x-coordinate difference at $79, and ERIC's character number at $7B.
$0F07 LDA $07
$0F09 STA $7B
Next we check whether EINSTEIN is in range.
$0F0B LDA #$11 Character number $11 is EINSTEIN. Store this potential target character number at $07.
$0F0D STA $07
$0F0F JSR $0D67 Is EINSTEIN close to the teacher?
$0F12 BCC $0F40 Branch if not to check BOY WONDER.
$0F14 LDA #$78 Prepare to address EINSTEIN's character buffer at $8960.
$0F16 CLC
$0F17 ADC $07
$0F19 STA $4F
$0F1B LDA #$60
$0F1D STA $4E
$0F1F LDY #$01 Pick up EINSTEIN's x-coordinate from his character buffer and store it at $0B.
$0F21 LDA ($4E),Y
$0F23 STA $0B
$0F25 CMP $FC Is it less than the teacher's x-coordinate?
$0F27 BCC $0F2F Branch if so.
$0F29 SEC Now A holds the difference between the teacher's and EINSTEIN's x-coordinates.
$0F2A SBC $FC
$0F2C JMP $0F34 Jump forward.
$0F2F LDA $FC Pick up the teacher's x-coordinate from $FC.
$0F31 SEC Now A holds the difference between the teacher's and EINSTEIN's x-coordinates.
$0F32 SBC $0B
$0F34 STA $7A Store this x-coordinate difference at $7A.
$0F36 CMP $79 Is it greater than any x-coordinate difference already calculated?
$0F38 BCS $0F40 Branch if so.
$0F3A STA $79 Otherwise store this new minimum x-coordinate difference at $79, and EINSTEIN's character number at $7B.
$0F3C LDA $07
$0F3E STA $7B
Next we check whether BOY WONDER is in range.
$0F40 LDA #$10 Character number $11 is BOY WONDER. Store this potential target character number at $07.
$0F42 STA $07
$0F44 JSR $0D67 Is BOY WONDER close to the teacher?
$0F47 BCC $0F75 Branch if not to check ANGELFACE.
$0F49 LDA #$78 Prepare to address BOY WONDER's character buffer at $8860.
$0F4B CLC
$0F4C ADC $07
$0F4E STA $4F
$0F50 LDA #$60
$0F52 STA $4E
$0F54 LDY #$01 Pick up BOY WONDER's x-coordinate from his character buffer and store it at $0B.
$0F56 LDA ($4E),Y
$0F58 STA $0B
$0F5A CMP $FC Is it less than the teacher's x-coordinate?
$0F5C BCC $0F64 Branch if so.
$0F5E SEC Now A holds the difference between the teacher's and BOY WONDER's x-coordinates.
$0F5F SBC $FC
$0F61 JMP $0F69 Jump forward.
$0F64 LDA $FC Pick up the teacher's x-coordinate from $FC.
$0F66 SEC Now A holds the difference between the teacher's and BOY WONDER's x-coordinates.
$0F67 SBC $0B
$0F69 STA $7A Store this x-coordinate difference at $7A.
$0F6B CMP $79 Is it greater than any x-coordinate difference already calculated?
$0F6D BCS $0F75 Branch if so.
$0F6F STA $79 Otherwise store this new minimum x-coordinate difference at $79, and BOY WONDER's character number at $7B.
$0F71 LDA $07
$0F73 STA $7B
Finally we check whether ANGELFACE is in range.
$0F75 LDA #$0F Character number $0F is ANGELFACE. Store this potential target character number at $07.
$0F77 STA $07
$0F79 JSR $0D67 Is ANGELFACE close to the teacher?
$0F7C BCC $0FAA Branch if not.
$0F7E LDA #$78 Prepare to address ANGELFACE's character buffer at $8760.
$0F80 CLC
$0F81 ADC $07
$0F83 STA $4F
$0F85 LDA #$60
$0F87 STA $4E
$0F89 LDY #$01 Pick up ANGELFACE's x-coordinate from his character buffer and store it at $0B.
$0F8B LDA ($4E),Y
$0F8D STA $0B
$0F8F CMP $FC Is it less than the teacher's x-coordinate?
$0F91 BCC $0F99 Branch if so.
$0F93 SEC Now A holds the difference between the teacher's and ANGELFACE's x-coordinates.
$0F94 SBC $FC
$0F96 JMP $0F9E Jump forward.
$0F99 LDA $FC Pick up the teacher's x-coordinate from $FC.
$0F9B SEC Now A holds the difference between the teacher's and ANGELFACE's x-coordinates.
$0F9C SBC $0B
$0F9E STA $7A Store this x-coordinate difference at $7A.
$0FA0 CMP $79 Is it greater than any x-coordinate difference already calculated?
$0FA2 BCS $0FAA Branch if so.
$0FA4 STA $79 Otherwise store this new minimum x-coordinate difference at $79, and ANGELFACE's character number at $7B.
$0FA6 LDA $07
$0FA8 STA $7B
Having checked whether ERIC, EINSTEIN, BOY WONDER and ANGELFACE are in range, we now see which (if any) is closest to the teacher.
$0FAA INC $79 Were any of the main kids within lines-receiving range?
$0FAC BEQ $0FB9 Return if not.
$0FAE LDA $7B Pick up the character number of the closest main kid and store it at $72.
$0FB0 STA $72
$0FB2 LDA #$08 Lines reprimand $08: NOW DON'T DO IT AGAIN.
$0FB4 STA $D8 Store this lines reprimand identifier at $D8.
$0FB6 JMP $1DB7 Make the teacher gives lines to the closest main kid.
$0FB9 RTS
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