Routines
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BF45: Generate Random Number
Used by the routines at Events_Elf, Events_FlyingLizard, Events_KorlWarrior and Action_Kill.
Returns a number from 00 up to, but not including, A.
The frame counter chooses how far to walk around that range.
Input
A Exclusive upper bound
Output
A The generated number
Mix the frame counter into a number below the limit in A.
GenerateRandomNumber BF45 PUSH BC Stash BC on the stack.
BF46 LD C,A Store the exclusive upper bound in C.
BF47 LD A,($5C78) Load *FRAMES into B as the loop count.
BF4A LD B,A
BF4B LD A,C Restore the exclusive upper bound into A.
GenerateRandomNumber_Loop BF4C DEC A Decrease the walking value by one.
BF4D JR NZ,GenerateRandomNumber_Next Jump to GenerateRandomNumber_Next if it has not wrapped past zero.
BF4F LD A,C Wrap back to the exclusive upper bound.
GenerateRandomNumber_Next BF50 DJNZ GenerateRandomNumber_Loop Decrease the frame-count loop by one and loop back to GenerateRandomNumber_Loop until the count is zero.
BF52 DEC A Decrease the result by one so the range starts at 00.
BF53 POP BC Restore BC from the stack.
BF54 RET Return.
View the equivalent code in;
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