Re: A86: 28F0 and parser

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Re: A86: 28F0 and parser



On Sat, 16 May 1998 23:33:15 -0400 Stephen Hicks <shicks@mindspring.com>
writes:
>
>rabidcow@juno.com wrote:
>
>> On Sat, 16 May 1998 22:02:27 -0400 Stephen Hicks 
><shicks@mindspring.com>
>> writes:
>> >
>> >Where does $28F0 get the address to ret to?  I've not been able to
>> >follow it.
>>
>> it skips one, it returns up an extra level, like it returns twice or 
>pops
>> one return address before returning.
>
>So if the stack is:F0 28 07 21 2D 25
>then it was called from 2D21?

the stack only works two bytes at a time.  it would return to 252D

>
>> >
>> >Also, I've been doing quite a bit of disassembling in the parser 
>and
>> >I've found these two routines on page D:
>> >
>> >$4C6B
>> >$53AE
>>
>> i can't get them to work, what sort of string do they parse?  i 
>tried
>> creating a string with "sin 30" and i couldn't get anything except 
>after
>> $4C6B there was an error.
>
>Then you've gotten farther than me.  This is what I've been doing - I 
>look in
>the VAT for #, and then I went to it and edited it (make sure to 
>change the
>size byte).  I've just tried arithmetic because i know that "1+3" 
>should
>become "D1",0,$60,"D3",0 and "12.4-6.4" should parse to
>"D12.4",0,$61,"D6.4",0.  T make a little asm program, breakpoint 
>$D748, edit
>#, edit $D748 to say call whatever and then breakpoint after the call.
>something is messing up tho...

well, not really.  i just set a variable and called those.  is there a
list somewhere of the tokens?  does the 53ae call work with #?  i can't
tell that it does anything with other strings.  maybe it needs some
registers set?

-josh

>>
>> >
>> >I believe they both take an input of a variable in OP1 that has the
>> >input in it (i.e. OP1->VAT entry for #, etc...).  I think the first
>> >one
>> >takes a parsed string and evaluates it, and I think the second one
>> >takes
>> >an unparsed string and parses it.  I'm not sure however.  On ROM
>> >version
>> >1.2, they correspond to $59FD on page 3 and $5DEB on page 9,
>> >respectively.  If anyone can take a look at these and find out when 
>it
>> >is called, where it is called from, what it does, etc. it'd really
>> >help.
>> >
>> >TIA,
>> >Stephen Hicks
>> >mailto:shicks@mindspring.com
>> >ICQ:5453914
>> >IRC/AIM:Kupopo
>> >Hopemage:http://www.mindspring.com/~shicks/
>> >
>> >
>> >
>>
>> 
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>
>
>
>--
>Stephen Hicks
>mailto:shicks@mindspring.com
>ICQ:5453914
>IRC/AIM:Kupopo
>Hopemage:http://www.mindspring.com/~shicks/
>
>
>

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