digitalmars.D - How to fix the mismatch struct size
- test123 (63/63) May 15 2022 ```c
- test123 (2/3) May 15 2022 and VTermStringFragment for mingw-x86 size is 12.
- test123 (3/7) May 15 2022 VTerm->parser for mingw-x64 clang size is 144, fox unix-64 is 208.
- Arjan (9/17) May 16 2022 Without fully scrutinizing your code I suspect the issues you see
```c
typedef struct {
const char *str;
size_t len : 30;
bool initial : 1;
bool final : 1;
} VTermStringFragment;
struct VTerm
{
const VTermAllocatorFunctions *allocator;
void *allocdata;
int rows;
int cols;
struct {
unsigned int utf8:1;
unsigned int ctrl8bit:1;
} mode;
struct {
enum VTermParserState {
NORMAL,
CSI_LEADER,
CSI_ARGS,
CSI_INTERMED,
DCS_COMMAND,
/* below here are the "string states" */
OSC_COMMAND,
OSC,
DCS,
APC,
PM,
SOS,
} state;
bool in_esc : 1;
int intermedlen;
char intermed[INTERMED_MAX];
union {
struct {
int leaderlen;
char leader[CSI_LEADER_MAX];
int argi;
long args[CSI_ARGS_MAX];
} csi;
struct {
int command;
} osc;
struct {
int commandlen;
char command[CSI_LEADER_MAX];
} dcs;
} v;
const VTermParserCallbacks *callbacks;
void *cbdata;
bool string_initial;
} parser;
}
```
VTermStringFragment for mingw-x64 clang size is 24, for unix-64
is 16.
VTerm for mingw-x64 clang size is 144, fox unix-64 is 208.
VTerm for mingw-x86 clang size is 128.
and offsetoff also diff from unix.
how to translate this into D struct ?
Is this problem cause by clang has wrong layout?
May 15 2022
On Monday, 16 May 2022 at 05:57:33 UTC, test123 wrote:Is this problem cause by clang has wrong layout?and VTermStringFragment for mingw-x86 size is 12.
May 15 2022
test123 <test123 gmail.com> On Monday, 16 May 2022 at 05:58:17 UTC, test123 wrote:On Monday, 16 May 2022 at 05:57:33 UTC, test123 wrote:VTerm->parser for mingw-x64 clang size is 144, fox unix-64 is 208. VTerm->parser for mingw-x86 clang size is 128.Is this problem cause by clang has wrong layout?and VTermStringFragment for mingw-x86 size is 12.
May 15 2022
On Monday, 16 May 2022 at 05:57:33 UTC, test123 wrote:
```c
typedef struct {
const char *str;
size_t len : 30;
bool initial : 1;
bool final : 1;
} VTermStringFragment;
[...]
Without fully scrutinizing your code I suspect the issues you see
are caused by:
- alignment
- struct context pointer
see:
https://dlang.org/spec/attribute.html#align
and
https://dlang.org/spec/attribute.html#static
May 16 2022
On Monday, 16 May 2022 at 07:29:39 UTC, Arjan wrote:On Monday, 16 May 2022 at 05:57:33 UTC, test123 wrote: Without fully scrutinizing your code I suspect the issues you see are caused by: - alignmentI know it is cause by alignment. my problem how to deal with diff alignment with diff platform. special when there is multi level nested struct.- struct context pointerThere is no struct context pointer since I translate all nested struct and union into static. struct work for linux with clang, but not for windows.
May 16 2022
On Monday, 16 May 2022 at 12:51:01 UTC, test123 wrote:On Monday, 16 May 2022 at 07:29:39 UTC, Arjan wrote:Nesting does not make a difference in c/c++, it does however in D.On Monday, 16 May 2022 at 05:57:33 UTC, test123 wrote: Without fully scrutinizing your code I suspect the issues you see are caused by: - alignmentI know it is cause by alignment. my problem how to deal with diff alignment with diff platform. special when there is multi level nested struct.That is not shown in the code.- struct context pointerThere is no struct context pointer since I translate all nested struct and union into static.struct work for linux with clang, but not for windows.Its it not clear what you want to achieve, assuming you want these structs to be equal (binary compatible layout on systems with same endianness) - enforce in C/C++ the alignment to byte/word/dword/qword alignment. This could be done with compiler `#pragma pack` or from C++/11 `alignas` or c/11 `_Alignas` (see https://en.cppreference.com/w/cpp/language/alignas) to make sure the padding is the same. - **do not** use bitfields since the packing of adjacent fields is implementation (compiler) dependent. (most probably the cause for diff in size 16 <==> 24 as you observed) see https://en.cppreference.com/w/cpp/language/bit_field - make sure the type's used in the struct are architecture independent, size of int in c/c++ is dependent on target arch x86=> 32bits x86_64 64bits. Its fixed in D. - make sure the size_t is the same type and size for all platforms - use static struct in D - use the correct corresponding types https://dlang.org/spec/type.html in D or use core.stdc.stdint type aliases
May 16 2022
On Monday, 16 May 2022 at 15:28:42 UTC, Arjan wrote:- enforce in C/C++ the alignment to byte/word/dword/qword alignment. This could be done with compiler `#pragma pack` or from C++/11 `alignas` or c/11 `_Alignas` (see https://en.cppreference.com/w/cpp/language/alignas) to make sure the padding is the same. - **do not** use bitfields since the packing of adjacent fields is implementation (compiler) dependent. (most probably the cause for diff in size 16 <==> 24 as you observed) see https://en.cppreference.com/w/cpp/language/bit_field - make sure the type's used in the struct are architecture independent, size of int in c/c++ is dependent on target arch x86=> 32bits x86_64 64bits. Its fixed in D. - make sure the size_t is the same type and size for all platforms - use static struct in D - use the correct corresponding types https://dlang.org/spec/type.html in D or use core.stdc.stdint type aliasesI can not change c struct since I don't own the project but need deal with it. All subtype size is matched that is why posix test work (and also check offsetof is matched). The problem is even all subtype size is same, but not all platform has same memory layout.
May 17 2022
On Tuesday, 17 May 2022 at 09:40:40 UTC, test123 wrote:On Monday, 16 May 2022 at 15:28:42 UTC, Arjan wrote:Maybe `extern(Windows)` can do something? Also, maybe useful : https://forum.dlang.org/post/ktntbwppqgbbajpbmrcf forum.dlang.org[...]I can not change c struct since I don't own the project but need deal with it. All subtype size is matched that is why posix test work (and also check offsetof is matched). The problem is even all subtype size is same, but not all platform has same memory layout.
May 17 2022
On Tuesday, 17 May 2022 at 09:40:40 UTC, test123 wrote:On Monday, 16 May 2022 at 15:28:42 UTC, Arjan wrote:Do you know how this 'c' part is build? Which compiler and compiler flags? Than you should be able to 'deduce' the alignment used an possibly the packing of bitfields. When you know these things you are able to craft the D equivalent. Another option is just to figure out the layout at runtime using a on purpose filled struct from 'c' with 'marker patterns' in the struct fields.- enforce in C/C++ the alignment to byte/word/dword/qword alignment. This could be done with compiler `#pragma pack` or from C++/11 `alignas` or c/11 `_Alignas` (see https://en.cppreference.com/w/cpp/language/alignas) to make sure the padding is the same. - **do not** use bitfields since the packing of adjacent fields is implementation (compiler) dependent. (most probably the cause for diff in size 16 <==> 24 as you observed) see https://en.cppreference.com/w/cpp/language/bit_field - make sure the type's used in the struct are architecture independent, size of int in c/c++ is dependent on target arch x86=> 32bits x86_64 64bits. Its fixed in D. - make sure the size_t is the same type and size for all platforms - use static struct in D - use the correct corresponding types https://dlang.org/spec/type.html in D or use core.stdc.stdint type aliasesI can not change c struct since I don't own the project but need deal with it.
May 17 2022
On Tuesday, 17 May 2022 at 10:05:21 UTC, Tejas wrote:Maybe `extern(Windows)` can do something? Also, maybe useful : https://forum.dlang.org/post/ktntbwppqgbbajpbmrcf forum.dlang.orgIt is extern(C). On Tuesday, 17 May 2022 at 19:52:23 UTC, Arjan wrote:Do you know how this 'c' part is build? Which compiler and compiler flags?Clang with makefile.Than you should be able to 'deduce' the alignment used an possibly the packing of bitfields.no alignment is settings from C source file.Another option is just to figure out the layout at runtime using a on purpose filled struct from 'c' with 'marker patterns' in the struct fields.sound like a solution, but not how to do this.
May 17 2022
On Wednesday, 18 May 2022 at 04:08:57 UTC, test123 wrote:On Tuesday, 17 May 2022 at 10:05:21 UTC, Tejas wrote:As can be observed from your first post, clang x64 does not pack all the bitields in the `VTermStringFragment` since the size is 24 bytes. alignment seems to be on address size (64bits 8bytes) Check the size of the other struct with bitfields `Vterm.mode` in the c program and the position of the bitfields if packed. With that information you should be able to create a matching layout in D.Maybe `extern(Windows)` can do something? Also, maybe useful : https://forum.dlang.org/post/ktntbwppqgbbajpbmrcf forum.dlang.orgIt is extern(C). On Tuesday, 17 May 2022 at 19:52:23 UTC, Arjan wrote:Do you know how this 'c' part is build? Which compiler and compiler flags?Clang with makefile.Than you should be able to 'deduce' the alignment used an possibly the packing of bitfields.no alignment is settings from C source file.Another option is just to figure out the layout at runtime using a on purpose filled struct from 'c' with 'marker patterns' in the struct fields.sound like a solution, but not how to do this.
May 17 2022