• VitaliiY (25/25) Jun 15 2021 Could anybody help with translation of this C macro to D
• =?UTF-8?Q?Ali_=c3=87ehreli?= (5/6) Jun 15 2021 If possible in your use case, I would put those variables in a struct
• VitaliiY (2/8) Jun 15 2021 Thank you, Ali! Idea with member function seems interesting.
• Dennis (37/40) Jun 15 2021 If the code duplication isn't too bad, consider just expanding
• VitaliiY (3/16) Jun 15 2021 Thank you, Dennis. I tried with this kind of mixin, but a, b -
• Tejas (3/22) Jun 16 2021 Use the

VitaliiY <yvitaliy1980 yandex.ru> writes:

Could anybody help with translation of this C macro to D 
mixin/mixin template? Here a - unsigned char, b - int. It's 
simple with STARTDATA as mixin, but STOREBITS and ADDBITS use 
variables defined in STARTDATA scope, so I can't understand how 
to do mixin template with it.

     #define STARTDATA \
       size_t ressize=0; \
       char *blockstart; \
       int numbits; \
       uint64_t bitbuffer=0;

     #define STOREBITS \
       while(numbits >= 8) \
       { \
         if(!size) return 0; \
         *(buffer++) = bitbuffer>>(numbits-8); \
         numbits -= 8; \
         ++ressize; \
         --size; \
       }

     #define ADDBITS(a, b) \
       { \
         bitbuffer = (bitbuffer<<(a))|((b)&((1<<a)-1)); \
         numbits += (a); \
         STOREBITS \
       }

=?UTF-8?Q?Ali_=c3=87ehreli?= <acehreli yahoo.com> writes:

On 6/15/21 5:18 AM, VitaliiY wrote:

 STOREBITS and ADDBITS use variables defined in STARTDATA

If possible in your use case, I would put those variables in a struct 
type and make add() a member function. However, a similar type already 
exists as std.bitmanip.BitArray.

Ali

VitaliiY <yvitaliy1980 yandex.ru> writes:

On Tuesday, 15 June 2021 at 12:38:15 UTC, Ali Çehreli wrote:
 On 6/15/21 5:18 AM, VitaliiY wrote:

 STOREBITS and ADDBITS use variables defined in STARTDATA

 If possible in your use case, I would put those variables in a 
 struct type and make add() a member function. However, a 
 similar type already exists as std.bitmanip.BitArray.

 Ali

Thank you, Ali! Idea with member function seems interesting.

Dennis <dkorpel gmail.com> writes:

On Tuesday, 15 June 2021 at 12:18:26 UTC, VitaliiY wrote:
 It's simple with STARTDATA as mixin, but STOREBITS and ADDBITS 
 use variables defined in STARTDATA scope, so I can't understand 
 how to do mixin template with it.

If the code duplication isn't too bad, consider just expanding 
the C macros and translating that. I've noticed that some C 
programmers like to use complex macros just to save 10 lines.

Otherwise, to make STOREBITS and ADDBITS access variables from 
STARTDATA, you can define them as inner functions.

```D
void f() {
     size_t ressize=0;
     char* blockstart;
     int numbits;
     ulong bitbuffer=0;

     size_t size;

     void storeBits() {
         while(numbits >= 8) {
             if(!size) return 0;
             *(buffer++) = bitbuffer>>(numbits-8);
             numbits -= 8;
             ++ressize;
             --size;
         }
     }
}
```

For the most literal translation, you can use a string mixin. You 
can't use a template mixin here since those can't insert code, 
only declarations.

```D
enum string ADDBITS(string a, string b) = `
{
     bitbuffer = (bitbuffer<<(`~a~`))|((`~b~`)&((1<<`~a~`)-1));
     numbits += (`~a~`);
     mixin(STOREBITS);
}`;

// on use: ADDBITS(varA, varB) becomes
mixin(ADDBITS!("varA", "varB"));
```

VitaliiY <yvitaliy1980 yandex.ru> writes:

On Tuesday, 15 June 2021 at 12:39:40 UTC, Dennis wrote:
 On Tuesday, 15 June 2021 at 12:18:26 UTC, VitaliiY wrote:
 [...]
 ```D

 enum string ADDBITS(string a, string b) = `
 {
     bitbuffer = (bitbuffer<<(`~a~`))|((`~b~`)&((1<<`~a~`)-1));
     numbits += (`~a~`);
     mixin(STOREBITS);
 }`;

 // on use: ADDBITS(varA, varB) becomes
 mixin(ADDBITS!("varA", "varB"));
 `

 [...]

Thank you, Dennis. I tried with this kind of mixin, but a, b - 
are type of 'int so it's confusing to use them as mixin arguments.

Tejas <notrealemail gmail.com> writes:

On Wednesday, 16 June 2021 at 05:48:21 UTC, VitaliiY wrote:
 On Tuesday, 15 June 2021 at 12:39:40 UTC, Dennis wrote:
 On Tuesday, 15 June 2021 at 12:18:26 UTC, VitaliiY wrote:
 [...]
 ```D

 enum string ADDBITS(string a, string b) = `
 {
     bitbuffer = (bitbuffer<<(`~a~`))|((`~b~`)&((1<<`~a~`)-1));
     numbits += (`~a~`);
     mixin(STOREBITS);
 }`;

 // on use: ADDBITS(varA, varB) becomes
 mixin(ADDBITS!("varA", "varB"));
 `

 [...]

 Thank you, Dennis. I tried with this kind of mixin, but a, b - 
 are type of 'int so it's confusing to use them as mixin 
 arguments.


Use the 
[.stringof](https://dlang.org/spec/property.html#stringofhttps://dlang.org/spec/pro
erty.html#stringof) property. That should do it.