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How SerenityOS declares ssize_t

awesomekling.github.io

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Re: How SerenityOS declares ssize_t

#51

Post by [deleted] »

rkangel wrote: post #49
kazinator wrote: post #25

I would do it like this: #if SIZEOF_SIZE_T == 8 typedef int64_t ssize_t #elif SIZEOF_SIZE_T == 4 typedef int32_t ssize_t #elif SIZEOF_SIZE_T == 2 // LOL typedef int16_t ssize_t #else #error port me! #endif SIZEOF_SIZE_T can be obtained using a script which compiles a test program without executing it. Over they years I used more than one approach, settling on this one: https://www.kylheku.com/cgit/txr/tree/configure?…

> #elif SIZEOF_SIZE_T == 2 // LOL Fun fact - for a while, this was true for the third most popular processor architecture in the world, one that most people haven't heard of. CSR (the bluetooth chip maker) was originally a spin-out from Cambridge Consultants, and their chips were for years based on a Cambridge Consultants processer design called XAP. As CSR had made billions of devices, XAP was likely right up there…

[deleted]

Re: How SerenityOS declares ssize_t

#52

Post by Y_Y »

Cthulhu_ wrote: post #41

I'm not a C developer at all, but this looks like bragging about a clever trick; when it comes to these things (and most code for that matter), I'd avoid clever tricks like the plague. Just write it out logically and as simple as possible. You're not saving much time / effort by writing out, and clear is better than clever. Code size is never an issue.

It's fun though. It's nice to have "best practices" etc, but SerenityOS isn't for IBM calculators or NASA life-support systems, it's a project for enjoyment by people who enjoy writing software.

Re: How SerenityOS declares ssize_t

#53

Post by 0xfedbee »

Cthulhu_ wrote: post #41

I'm not a C developer at all, but this looks like bragging about a clever trick; when it comes to these things (and most code for that matter), I'd avoid clever tricks like the plague. Just write it out logically and as simple as possible. You're not saving much time / effort by writing out, and clear is better than clever. Code size is never an issue.

You’d understand it if you were a C developer.

Re: How SerenityOS declares ssize_t

#54

Post by consp »

rkangel wrote: post #49
kazinator wrote: post #25

I would do it like this: #if SIZEOF_SIZE_T == 8 typedef int64_t ssize_t #elif SIZEOF_SIZE_T == 4 typedef int32_t ssize_t #elif SIZEOF_SIZE_T == 2 // LOL typedef int16_t ssize_t #else #error port me! #endif SIZEOF_SIZE_T can be obtained using a script which compiles a test program without executing it. Over they years I used more than one approach, settling on this one: https://www.kylheku.com/cgit/txr/tree/configure?…

> #elif SIZEOF_SIZE_T == 2 // LOL Fun fact - for a while, this was true for the third most popular processor architecture in the world, one that most people haven't heard of. CSR (the bluetooth chip maker) was originally a spin-out from Cambridge Consultants, and their chips were for years based on a Cambridge Consultants processer design called XAP. As CSR had made billions of devices, XAP was likely right up there…

I also remember the 8051 based TI bluetooth chips which also have some "weird" things going on and has a harvard like architecture just with more memory types. I raise you three types: program memory is also 24bit (using both one 8bit and the 16bit register) and 16bit "external" memory and 256 bytes of mapped registers.

I don't know if the compiler actually does this as different types and how it internally handles it. Maybe someone can elaborate on that.

Re: How SerenityOS declares ssize_t

#55

Post by jabl »

addaon wrote: post #32
dataflow wrote: post #26

Earlier quoted context omitted.

> see ones complement I'm glad you brought this up because is kind of my point. C++ realized this was useless baggage and finally left it behind. [1] I don't see why ptrdiff_t is much different here. C just doesn't want to let things to, I guess. Literally any feature you put into a language will end up being used (or abused) by someone for something. "It's nice" that at some point in the future someone can pick up a…

It's a philosophy thing. There are plenty of languages that just solve for flat Von Neumann memory models. In the past, that did not describe all machines -- e.g. the pre-standard Borland C/C++ compilers for x86 real mode that used 32-bit ptrdiff_t and 16-bit size_t (which doesn't count as an answer because they were pre-standard in so many ways). In the future, it may or may not describe all machines -- it's possibl…

C23 follows C++ in requiring signed integers to have two's complement representation. I think by this point it's pretty much settled that it's the "optimal" way to implement signed integers. Now if we change to non-binary architectures (or something radically different) things might change, but at that point quite a lot of the C standard will have to be thrown out as well.

Re: How SerenityOS declares ssize_t

#58

Post by ghosty141 »

stathibus wrote: post #42
Cthulhu_ wrote: post #41

I'm not a C developer at all, but this looks like bragging about a clever trick; when it comes to these things (and most code for that matter), I'd avoid clever tricks like the plague. Just write it out logically and as simple as possible. You're not saving much time / effort by writing out, and clear is better than clever. Code size is never an issue.

Seriously, in what dimension is this a good choice?

SerenityOS is not production software or used for anything serious. Its just for fun.

Re: How SerenityOS declares ssize_t

#59

Post by mid-kid »

rkangel wrote: post #49
kazinator wrote: post #25

I would do it like this: #if SIZEOF_SIZE_T == 8 typedef int64_t ssize_t #elif SIZEOF_SIZE_T == 4 typedef int32_t ssize_t #elif SIZEOF_SIZE_T == 2 // LOL typedef int16_t ssize_t #else #error port me! #endif SIZEOF_SIZE_T can be obtained using a script which compiles a test program without executing it. Over they years I used more than one approach, settling on this one: https://www.kylheku.com/cgit/txr/tree/configure?…

> #elif SIZEOF_SIZE_T == 2 // LOL Fun fact - for a while, this was true for the third most popular processor architecture in the world, one that most people haven't heard of. CSR (the bluetooth chip maker) was originally a spin-out from Cambridge Consultants, and their chips were for years based on a Cambridge Consultants processer design called XAP. As CSR had made billions of devices, XAP was likely right up there…

It's also 16 bit for the AVR architecture used on Arduino devices.

Re: How SerenityOS declares ssize_t

#60

Post by magicalhippo »

rkangel wrote: post #49
kazinator wrote: post #25

I would do it like this: #if SIZEOF_SIZE_T == 8 typedef int64_t ssize_t #elif SIZEOF_SIZE_T == 4 typedef int32_t ssize_t #elif SIZEOF_SIZE_T == 2 // LOL typedef int16_t ssize_t #else #error port me! #endif SIZEOF_SIZE_T can be obtained using a script which compiles a test program without executing it. Over they years I used more than one approach, settling on this one: https://www.kylheku.com/cgit/txr/tree/configure?…

> #elif SIZEOF_SIZE_T == 2 // LOL Fun fact - for a while, this was true for the third most popular processor architecture in the world, one that most people haven't heard of. CSR (the bluetooth chip maker) was originally a spin-out from Cambridge Consultants, and their chips were for years based on a Cambridge Consultants processer design called XAP. As CSR had made billions of devices, XAP was likely right up there…

> sizeof(uint16_t) == 1

> This is all completely legal according to the C standard.

Is it? I don't have access to the standard, but from secondary sources[1] it seems not?

unsigned integer type with width of exactly 8, 16, 32 and 64 bits respectively (provided if and only if the implementation directly supports the type)

If it is, it kinda defeats the whole purpose of uint16_t and friends.

[1]: https://en.cppreference.com/w/c/types/integer

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