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Post by bigbass on Mar 31, 2013 0:52:54 GMT 1
I tried to do this in just BaCon using MEMORY
seems like a good way to do some things
and I wanted to post an example
we can read an address but we cant rewrite to it
the same way C code does with pointers
'==================
'the C code ported
' int i = 5;
'==================
i = 5
'============================================
' ip = &i the C code ported . FIRST STEP
' &i generates a pointer to i in two steps
'============================================
ip = ADDRESS(i)
PRINT "The address of i = " ,ip
'============================================
' the variable ip. points to i .SECOND STEP
'============================================
ip = i
PRINT "The value of i = ", ip
PRINT
PRINT "which would print 5, since ip points to i, and i is (at the moment) 5."
PRINT
PRINT "But the address of ip and the address of i are different ip =" , ADDRESS(ip)
PRINT " So ip doesn't really point to i it just has the same value stored"
PRINT
PRINT
' cant use pointers the same way so lets do it in memory
' do this in memory because using a "*" gives problems
OPTION MEMTYPE long
mem = MEMORY(500)
PRINT "===DO it in MEMORY ======"
PRINT "get the address of ip and store it in memory"
'---get the stored value from whats in the address of ip and store it in mem
POKE mem, PEEK(ADDRESS(ip))
PRINT "show the value of what is in memory "
'--- show the value of mem
PRINT PEEK(mem)
PRINT
PRINT "get the address of ip and store it in mem"
POKE mem,ADDRESS(ip)
'--- print the adress of ip
PRINT "the address of ip"
PRINT PEEK(mem)
PRINT
'====================================
' now set whatever ip points to 7
' *ip = 7; the C code ported
' a bit tricky but lets try
' mem is a dynamic variable but not a pointer
' that lets you change the value in an address
'====================================
POKE mem,7
PRINT "we can change whats in memory but "
PRINT "we can't change a value using a pointer"
PRINT PEEK(mem)
'clean up so we don't have memory leaks
FREE mem
PRINT "maybe we could rewrite some things "
PRINT "by doing it in memory"
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Post by Pjot on Mar 31, 2013 8:04:15 GMT 1
Thanks bigbass,
In the upcoming version you can also check if a memory address is legal (e.g. writeable/readable) or not.
IF MEMCHECK(12345) THEN PRINT "Right!"
ELSE PRINT "Wrong!"
mem = MEMORY(10)
IF MEMCHECK(mem) THEN PRINT "Right!"
ELSE PRINT "Wrong!"
BR,
Peter
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Post by bigbass on Apr 2, 2013 16:14:48 GMT 1
Thank you Peter for adding MEMCHECK ! will use a simple example explaining a pointer first then one for testing with MEMCHECK converted the info here to be used in Bacon syntax (it will be useful for embedding GTK) c-pointer.blogspot.mx/2009/11/what-is-pointer-in-c-programming.htmlJoe
a = 5
'(1) Meaning of following simple pointer declaration and definition:
'int a=5;
'int * ptr;
'ptr=&a;
'About variable a:
'1. Name of variable : a
'2. Value of variable which it keeps: 5
'3. Address where it has stored in memory : 1025 (assume)
'About variable ptr:
'4. Name of variable : ptr
'5. Value of variable which it keeps: 1025
'6. Address where it has stored in memory : 5000 (assume)
PRINT "The address of a"
address_of_a = ADDRESS(a)
PRINT address_of_a
PRINT
PRINT "ptr has the address of a "
ptr = ADDRESS(a)
PRINT ptr
PRINT
PRINT "The address of ptr "
address_of_ptr = ADDRESS(ptr)
PRINT address_of_ptr
PRINT
PRINT "The value of a "
PRINT a
PRINT
PRINT "lets do a MEMCHECK for a"
IF MEMCHECK(ADDRESS(a)) THEN PRINT "Right!"
ELSE PRINT "Wrong!"
PRINT
mem = MEMORY(10)
PRINT "lets do a MEMCHECK for mem"
IF MEMCHECK(mem) THEN PRINT "Right!"
ELSE PRINT "Wrong!"
PRINT
'clean up so we don't have memory leaks
FREE mem
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Post by vovchik on Apr 2, 2013 18:01:39 GMT 1
Dear Joe, Nice work - as usual. I think you could also demonstrate two as yet unritten functions that might be useful for everybody: BLOAD and BSAVE, as in old M$ Basic, using memory. You could read in a bin file to memory, play with it as a var and write back it back.  With thanks and kind regards, vovchik |
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Post by bigbass on Apr 3, 2013 16:00:07 GMT 1
Hey vovchik That sounds interesting Peter has this www.basic-converter.org/bindump.bacwhich is nice because so this could be the base code to read in a binary then modify it for any special use more info and examples Joe |
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Post by vovchik on Apr 3, 2013 18:17:14 GMT 1
Dear Joe, I experimented a while back and here are a few results (attached). Something there might be handy. With kind regards, vovchik Attachments:
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Post by bigbass on Apr 4, 2013 6:02:00 GMT 1
Hello vovchik
Thanks for posting some example programs !
that's the idea of this thread a place for everyone to
post code examples that use MEMORY
or manipulate binary /hex /text data that could be read into MEMORY
great stuff
Joe
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Post by bigbass on Apr 4, 2013 17:40:41 GMT 1
Please note this is BINDUMP original link below www.basic-converter.org/bindump.bac *with cosmetic changes only renamed to BINDUMP3 ' binary dump to ascii ' to show full screen ascii only no addresses and fully automatic view ' reduced code down only for a simple example to focus on the MEMORY code part ' for this thread interesting we can dump bacon compiled apps and look for errors or info another way to debug stuff
'
' *** BINDUMP3 - a universal binary dumper ***
'
' Sometimes I need to check a (text-)file with a binary viewer
' to see only ascii characters.
'
' We read the target program in chunks of 80 bytes instead of
' reading it into memory completely, to avoid memory overflow
' problems with really large files.
'
' PvE, February 2010 - GPL.
' Revised March 2012 - PvE.
'
' *cosmetic changes only Abril 4 2013 bigbass
' binary dump to ascii
' to show full screen ascii only no addresses and fully automatic view
' reduced code down only for a simple example to focus on the MEMORY code
' -------------------------------------------------------------------
'-----------------------
'--- INITALIZE MEMORY CODE
'-----------------------
' Chunks of 80 bytes to have a better full screen view removed address
CONST Chunk_Size = 80
' Declare as 'int' to avoid compiler warnings with FORMAT
DECLARE byte, counter, Total_Rows TYPE int
' Get the current amount of rows
IF ROWS > 0 THEN
Total_Rows = ROWS-2
ELSE
Total_Rows = 23
END IF
'-----------------------
'---Parse arguments to program
'-----------------------
SPLIT ARGUMENT$ BY " " TO arg$ SIZE dim
IF dim < 2 THEN
PRINT "Usage: bindump <file>"
END
ENDIF
prog$ = arg$[1]
' Check if file exists
IF NOT(FILEEXISTS(prog$)) THEN
PRINT "ERROR: file not found!"
END
END IF
'-----------------------
'--- START MEMORY CODE
'-----------------------
' This is the memory area which will be printed
Mem_Block = MEMORY(Chunk_Size)
' Start reading the file
OPEN prog$ FOR READING AS file
' Walk through file until end
WHILE NOT(ENDFILE(file)) DO
' Reset memory area to clean previous data
FOR i = 0 TO Chunk_Size - 1
POKE Mem_Block + i, 0
NEXT
' Set File Pointer to next position
SEEK file OFFSET counter*Chunk_Size
' Perform a binary read into our memory area
GETBYTE Mem_Block FROM file SIZE Chunk_Size
' Dump binary values as character on screen
FOR i = 0 TO Chunk_Size - 1
byte = PEEK(Mem_Block + i)
IF byte > 31 AND byte < 127 THEN PRINT CHR$(byte);
ELSE PRINT ".";
NEXT
' Next line and chunk
PRINT:INCR counter
WEND
'close all
CLOSE FILE file
FREE Mem_Block
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