Hi :)

I made this function to inverse the bytes in intger or T (possible) type...

int reverseBytes(T)(T val)
{
	int retVal = 0;
	static if(is(T == string))
		retVal = to!int(val);

	return (retVal & 0x000000FF) << 24 |
		   (retVal & 0x0000FF00) << 8 |
		   (retVal & 0x00FF0000) >> 8 |
		   (retVal & 0xFF000000) >> 24;
}

//...
writefln("%x", reverseBytes(x"00402030"));
//...

When I execute this program, I got this exception:
std.conv.ConvException@C:\D\dmd2\src\phobos\std\conv.d(1968): Unexpected '@' when converting from type string to type int

Alexandre:

> 	return (retVal & 0x000000FF) << 24 |
> 		   (retVal & 0x0000FF00) << 8 |
> 		   (retVal & 0x00FF0000) >> 8 |
> 		   (retVal & 0xFF000000) >> 24;

See also core.bitop.bswap.

Bye,
bearophile

Thanks, but, when I convert I recive a 'c' in the front of my number...

uint reverseBytes(uint val)
{
	import core.bitop : bitswap;

	return bitswap(val);
}

//...
writefln("%x", reverseBytes(0x00402030));
//...

// output: c040200

On Tuesday, 15 July 2014 at 12:16:26 UTC, bearophile wrote:
>
> See also core.bitop.bswap.
>
> Bye,
> bearophile

Alexandre:

> Thanks, but, when I convert I recive a 'c' in the front of my number...

This shows it inverts all bits, not just the four byte positions. I don't understand:


import core.bitop: bitswap;

uint reverseBytes(in uint val) pure nothrow @safe @nogc {
    return val.bitswap;
}

void main() {
    import std.stdio;

    immutable uint x = 0x_00_40_20_30U;
    immutable uint y = x.reverseBytes;
    writefln("%08x", x);
    writefln("%032b", x);
    writefln("%08x", y);
    writefln("%032b", y);
}


Bye,
bearophile

Something is wrong between our communication...

I am wanting to do something better to order the bytes, for this my code...
https://gist.github.com/bencz/3576dfc8a217a34c05a9

For example, in that case:
injectData(image[0x207], x"30204000");

It's more simple to use something like:
injectData(image[0x207], inverseBytes(0x00402030));


On Tuesday, 15 July 2014 at 13:15:34 UTC, bearophile wrote:
> Alexandre:
>
>> Thanks, but, when I convert I recive a 'c' in the front of my number...
>
> This shows it inverts all bits, not just the four byte positions. I don't understand:
>
>
> import core.bitop: bitswap;
>
> uint reverseBytes(in uint val) pure nothrow @safe @nogc {
>     return val.bitswap;
> }
>
> void main() {
>     import std.stdio;
>
>     immutable uint x = 0x_00_40_20_30U;
>     immutable uint y = x.reverseBytes;
>     writefln("%08x", x);
>     writefln("%032b", x);
>     writefln("%08x", y);
>     writefln("%032b", y);
> }
>
>
> Bye,
> bearophile

On 07/15/2014 04:56 AM, Alexandre wrote:

>          retVal = to!int(val);

> std.conv.ConvException@C:\D\dmd2\src\phobos\std\conv.d(1968): Unexpected
> '@' when converting from type string to type int

That means to!int failed because 'val' contained a '@' character in it:

import std.conv;

void main()
{
    auto s = "42@";    // <-- What is that?
    auto i = to!int(s);
}

However, there seems to be a bug in to(). It seems to incorrectly go one character ahead:

    to!int("mn");

"Unexpected 'n' when converting from type string to type int"

    to!int("m");

"Unexpected end of input when converting from type string to type int"

That is a bug, right?

So, in your case the unexpected '@' character may be after another unexpected one:

    to!int(" @");

"Unexpected '@' when converting from type string to type int"

Ali

Strange..., why '@' ?

PS: Ali Çehreli, thanks for your book, your book is wonderful!!!

On Tuesday, 15 July 2014 at 13:49:51 UTC, Ali Çehreli wrote:
> On 07/15/2014 04:56 AM, Alexandre wrote:
>
> >          retVal = to!int(val);
>
> > std.conv.ConvException@C:\D\dmd2\src\phobos\std\conv.d(1968):
> Unexpected
> > '@' when converting from type string to type int
>
> That means to!int failed because 'val' contained a '@' character in it:
>
> import std.conv;
>
> void main()
> {
>     auto s = "42@";    // <-- What is that?
>     auto i = to!int(s);
> }
>
> However, there seems to be a bug in to(). It seems to incorrectly go one character ahead:
>
>     to!int("mn");
>
> "Unexpected 'n' when converting from type string to type int"
>
>     to!int("m");
>
> "Unexpected end of input when converting from type string to type int"
>
> That is a bug, right?
>
> So, in your case the unexpected '@' character may be after another unexpected one:
>
>     to!int(" @");
>
> "Unexpected '@' when converting from type string to type int"
>
> Ali

On Tuesday, 15 July 2014 at 12:24:48 UTC, Alexandre wrote:
> Thanks, but, when I convert I recive a 'c' in the front of my number...
>
> uint reverseBytes(uint val)
> {
> 	import core.bitop : bitswap;
>
> 	return bitswap(val);
> }

You confused bswap with bitswap.
The former reverses bytes, the latter reverses bits.

If you look at bearophile's original message he says bswap.

On Tuesday, 15 July 2014 at 14:05:14 UTC, Alexandre wrote:
> Strange..., why '@' ?

because x"40" == "@"