Weirdness 4 - Printable Version

Weirdness 4 - Printable Version

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+---- Thread: Weirdness 4 (/showthread.php?tid=148)

Weirdness 4 - britlion - 2010-01-31

Okay, this one is pretty small. It crashes.

Code:
FUNCTION RAND () as uInteger : REM Code by Jon Ritman
    random: REM add 46 bytes to this location to hit the store "Lion"
    asm 
    RANDOM:     LD HL,(SEED+2)
                LD D,L
                ADD HL,HL
                ADD HL,HL
                LD C,H
                LD HL,(SEED)
                LD B,H
                RL B
                LD E,H
                RL E
                RL D
                ADD HL,BC
                LD (SEED),HL
                LD HL,(SEED+2)
                ADC HL,DE
                RES 7,H
                LD (SEED+2),HL
                JP M,RANDOM3
                LD HL,SEED
    RANDOM2:    INC (HL)
                    INC HL
                JR Z,RANDOM2
    RANDOM3:    LD HL,(SEED)              
                RET
    SEED:       DB "Lion"
    end asm
    
END FUNCTION
CLS                         
DIM  a as uInteger
    let a=@random
    PRINT a
    let a=a+46
    PRINT a

DIM n as uInteger
DIM result as uByte

FOR n=a to a+4
    LET result=peek n
    print n;"=";result;"=";CHR$ (result)
next n

IF I change the last line to:

Code:
print n;"=";result;"=";CHR$ (76)

It doesn't crash. What's the problem with CHR$(uByte) suddenly?

Can anyone else replicate this?

All I was trying to do was put in a nice shiny new random number generator...

Re: Weirdness 4 - boriel - 2010-02-21

britlion Wrote:Okay, this one is pretty small. It crashes.

Code:
FUNCTION RAND () as uInteger : REM Code by Jon Ritman random: REM add 46 bytes to this location to hit the store "Lion" asm RANDOM: LD HL,(SEED+2) LD D,L ADD HL,HL ADD HL,HL LD C,H LD HL,(SEED) LD B,H RL B LD E,H RL E RL D ADD HL,BC LD (SEED),HL LD HL,(SEED+2) ADC HL,DE RES 7,H LD (SEED+2),HL JP M,RANDOM3 LD HL,SEED RANDOM2: INC (HL) INC HL JR Z,RANDOM2 RANDOM3: LD HL,(SEED) RET SEED: DB "Lion" end asm END FUNCTION CLS DIM a as uInteger let a=@random PRINT a let a=a+46 PRINT a DIM n as uInteger DIM result as uByte FOR n=a to a+4 LET result=peek n print n;"=";result;"=";CHR$ (result) next n

IF I change the last line to:

Code:
print n;"=";result;"=";CHR$ (76)

It doesn't crash. What's the problem with CHR$(uByte) suddenly?

Can anyone else replicate this?

All I was trying to do was put in a nice shiny new random number generator...

This program does not crash to me. Try it with the new 1.2.5 Beta 2 version, anyway. It prints Lion# where # means rubbish.
The problem here is you're printing 5 chars (a, a+1, a+2, a+3, a+4) and Lion has 4 letters. You have an overflow in your print, so the glitched character is expected. But the program should not crash (It does not in my emulator).

Can you try with V 1.2.5 Beta 2?