SyntaxBomb - Indie Coders

( outitemp & 0x80 ? FLAG_N : 0 )


Does this mean that , If ( outitemp & 128) ie, if bit7 of outitemp is a 1 then it will be TRUE and if bit7 of outitemp is a 0 then it will be FALSE.

After the ? mark is this now a decision where we pick the value of either (FLAG_N or 0) dependinging on the TRUE or FALSE outcome?

If so which side of the : is TRUE or FALSE?

Or have i completely misunderstood?

Thanks in advance BAGGEY

Read
https://en.wikipedia.org/wiki/Ternary_conditional_operator

Quote from: dawlane on May 21, 2024, 18:39:04Read
https://en.wikipedia.org/wiki/Ternary_conditional_operator

Cool Link

I wish my learning curve would peterout! But it still feels exponential

Thankyou.

Could someone have ago at this line for me

unsigned char *buffer = (unsigned char*)malloc(SizeOf(unsigned char)*lSize)

I assume im getting a pointer to :byte maybe a Tbank of sorts where the buffer size is allocated or a resize? 

Baggey

Actually, in BASIC (which dialect? FreeBasic, for example, allows the ternary operations with the operator IIF) your second question could be easily implemented by making a string of length lSize

Quote from: Baggey on May 02, 2025, 19:17:03Could someone have ago at this line for me

unsigned char *buffer = (unsigned char*)malloc(SizeOf(unsigned char)*lSize)

I assume im getting a pointer to :byte maybe a Tbank of sorts where the buffer size is allocated or a resize? 

Baggey

Read it right to left
SizeOf(unsigned char)*lSize = Deal with the SizeOf function first. Size of unsigned char, the size of char depends on the compiler. But you can assume that for a majority of systems it is a byte. So you can read it a 1*lSize.

malloc(SizeOf(unsigned char)*lSize) = Reserve a block of memory on the heap that is 1*lSize bytes.

(unsigned char*)malloc(SizeOf(unsigned char)*lSize) = The block of memory needs to be cast to that of a pointer of unsigned char. So you need to get a pointer to the previously created memory block. There are a couple of functions in the TBank to do that: Function BankBuf:Byte Ptr( bank:TBank ) and Function LockBank:Byte Ptr( bank:TBank ).

So it would translate into something like this in BlitzMax:
Local buffer:Byte Ptr = BankBuf(CreateBank(Sizeof(Byte)*lSize))

Remember that you may have to keep track of the pointer and the memory block.

Note that I have not tested this, as it was off the top of my head.

EDIT:
Const bSize:Byte = 0
Local buffer:Byte Ptr = BankBuf(CreateBank(SizeOf(bSize) * lSize))

This should be the equivalent to the C code. SizeOf(Byte) throws an error, so you will need a few variables of the size of each data type  to be used. And remember to use the correct Peek/Poke functions for the number of bytes to read and write.

Note: You may have to create the memory bank with it's own identifier to avoid a memory leak. See the advanced memory stuff in the docs.

The first one in "Basic" seems to be just a variant on "if..then..else" and the second one could have a variety of uses including declaring an array of bytes, or even just declaring a fixed length string variable with chars of a certain size (eg UTF could have 2 byte chars for instance).

I could be wrong and I don't know what you're using these for but that's how I saw it.

Thankyou for the thoughts an ideas always appreciated. 

QuoteRemember that you may have to keep track of the pointer and the memory block.

By the sounds of it i wern't far of. I remember doing something with the .d64 reader where id start an array at size 1 using a list. And as i added to that said list, i would then have to reasign the pointers excetera. Or the info being returned was curupted.

Still that gives me an idea how to tackle it.

Kind Regards Baggey

I cannot wait till you ask about converting a union. That one would be a bit complicated with how they work.

I seem to remember using pointers not being exactly garbage collector friendly in BlitzMax.
My memory is a bit fuzzy but I think you have to temporarily disable the garbage in some cases.
The theory being the pointer can reference something it can then be garbage collected immediately and you've got a bad reference.

Anyone correct me if I'm wrong.