| Routines

748C: Make a sound effect

Used by the routines at 7118, 7414, 74C8, 7854 and 7EB1.
Input
A | Initial border colour
B | Pitch
C | 0x10 + next border colour
DE | Duration
748C | PUSH HL |
748D | LD L,B | Save the pitch parameter in L
748E | OUT ($FE),A | Flip the border colour and the state of the speaker
7490 | XOR C
7491 | LD B,L | This is the pitch timing delay
7492 | DJNZ $7492
7494 | DEC E | Jump back unless the sound effect is finished
7495 | JR NZ,$748E
7497 | DEC D
7498 | JR NZ,$748E
749A | LD A,$01 | BORDER 1 (blue) before returning
749C | OUT ($FE),A
749E | POP HL |
749F | RET |