Skool Daze: Routine at 7C6E

7C6E: Make a teacher perform dinner duty (1)

Used by command list 0xB8. Makes the teacher on dinner duty pace up and down the dinner hall, checking whether ERIC is present. If ERIC is absent, the teacher is sent to find him, after which the command list is restarted.

Input
H	0xA3 (MR WACKER) or 0xA5 (MR WITHIT)

7C6E

LD DE,$7FC8

Set bit 7 at 7FC8, indicating that dinner has started (and so ERIC should be in the dinner hall)

7C71

EX DE,HL

7C72

SET 7,(HL)

7C74

EX DE,HL

This entry point is used on subsequent calls when the teacher on dinner duty has reached the right end of the dinner hall.

7C75

CALL $79D4

Set the zero flag if ERIC is where he should be

7C78

LD DE,$9721

D=0x97 (LSB of 7C97), E=33 (x-coordinate of the left end of the teacher's dinner duty orbit)

This entry point is used by the routine at 7C97 with D=0x75 (LSB of the entry point at 7C75, above) and E=62 (x-coordinate of the right end of the teacher's dinner duty orbit), and also by the routine at F300 with the zero flag reset.

7C7B

LD L,$69

7C7D

JR Z,$7C87

Jump if ERIC is where he should be

7C7F

LD (HL),$A0

Place the address of the interruptible subcommand routine at 7BA0 into bytes 0x69 and 0x6A of the character's buffer

7C81

INC L

7C82

LD (HL),$7B

7C84

JP $7BA0

And jump to that routine now

ERIC is where he should be, so there's no need to chase him.

7C87

LD (HL),$3C

Place the address of the interruptible subcommand routine at 633C into bytes 0x69 and 0x6A of the teacher's buffer

7C89

INC L

7C8A

LD (HL),$63

7C8C

INC L

Place 33 or 62 into byte 0x6B of the teacher's buffer (to make him go to that x-coordinate next)

7C8D

LD (HL),E

7C8E

INC L

Place 0 into byte 0x6C of the teacher's buffer, giving him more than enough time to reach the other end of the dinner hall without interruption

7C8F

LD (HL),$00

7C91

LD L,$63

Replace the address of this primary command routine in bytes 0x63 and 0x64 of the teacher's buffer with that of 7C97 or 7C75

7C93

LD (HL),D

7C94

JP $633C

Proceed to the other end of the dinner hall