I have started to wrap the Sundials project and my first goal was to wrap the
N_Vector shared library, which I to some extent has succeeded with but in a
rather hacky, and not so seamless, way. The structure of the files can be found
in my github repo:
[https://github.com/HugoGranstrom/nimsundials](https://github.com/HugoGranstrom/nimsundials).
The headers are in the include/ folder and the shared library is in the lib/
folder. The file I'm writing all the code below in is located at the root of
the repo and is called nvector.nim. I wondered if there is another way of doing
it. I have tried to solve it in various ways which are shown below, and only
the last one worked.
The only thing that differs between the different versions are how the headers
are imported so this is the main structure of the file:
import os, strformat
import nimterop/[cimport, paths]
const srcDir = currentSourcePath().parentDir()
const inclDir = srcDir/"include"
const libDir = srcDir/"lib"
static:
cDebug()
cDisableCaching()
cIncludeDir(srcDir/"include")
cIncludeDir(srcDir/"include/nvector")
cIncludeDir(srcDir/"include/sundials")
cIncludeDir(srcDir/"lib")
cPlugin:
import strutils
proc onSymbol*(sym: var Symbol) {.exportc, dynlib.} =
if sym.kind == nskType:
if sym.name == "_N_VectorContent_Serial":
sym.name = "N_VectorContent_Serial_Base"
sym.name = sym.name.strip(chars = {'_'})
const
libsundials_nvecserial = libDir/"libsundials_nvecserial.dll"
#######################
#######################
Insert the different codes here
#######################
#######################
type
NVectorType* = object
length*: int
rawVector*: ref[N_Vector]
template ptr2Array[T](p: pointer): auto = cast[ptr UncheckedArray[T]](p)
template array2Ptr[T](arr: openArray[T]): auto = addr(arr[0])
template `->`(a, b: untyped): untyped =
a[].b
template NV_CONTENT_S(v: untyped): untyped =
cast[N_VectorContent_Serial](v->content)
template NV_LENGTH_S(v: untyped): untyped = NV_CONTENT_S(v) -> length
template NV_OWN_DATA_S(v: untyped): untyped = NV_CONTENT_S(v) -> own_data
template NV_DATA_S(v: untyped): untyped = NV_CONTENT_S(v) -> data
template NV_Ith_S(v: untyped, i: sunindextype): untyped =
ptr2Array[realtype](NV_DATA_S(v))[i]
proc newNVector*(length: int): NVectorType =
if length <= 0:
raise newException(ValueError, "NVector length must be greater than
0")
result.length = length
result.rawVector = new N_Vector
result.rawVector[] = N_VNew_Serial(result.length)
var v = newNVector(3)
echo NV_LENGTH_S(v.rawVector[])
Run
Method 1:
cImport(inclDir/"nvector/nvector_serial.h", dynlib =
"libsundials_nvecserial", recurse = true)
Run
Here I try to link the dynamic library and recurse on it's #include-ed headers.
When I try to compile this it prints out the produced Nim code but then it
freezes here. I left it for an hour but nothing had happened:
CC: stdlib_system.nim
CC: nvector.nim
Run
Method 2:
cImport(inclDir/"sundials/sundials_config.h")
cImport(inclDir/"sundials/sundials_types.h")
cImport(inclDir/"sundials/sundials_nvector.h")
cImport(inclDir/"nvector/nvector_serial.h", dynlib =
"libsundials_nvecserial")
Run
Now I manually import the headers it needs. Now I instead get this error:
CC: stdlib_system.nim
CC: nvector.nim
Error: execution of an external compiler program 'gcc.exe -c -w
-mno-ms-bitfields -DWIN32_LEAN_AND_MEAN
-IC:/Users/elev/code/nimsundials/include
-IC:/Users/elev/code/nimsundials/include/nvector
-IC:/Users/elev/code/nimsundials/include/sundials
-IC:/Users/elev/code/nimsundials/lib
-IC:\Users\elev\.choosenim\toolchains\nim-0.20.0\lib
-IC:\Users\elev\code\nimsundials -o
C:\Users\elev\nimcache\nvector_d\nvector.nim.c.o
C:\Users\elev\nimcache\nvector_d\nvector.nim.c' failed with exit code: 1
C:\Users\elev\nimcache\nvector_d\nvector.nim.c: In function 'NimMainModule':
C:\Users\elev\nimcache\nvector_d\nvector.nim.c:533:26: error: dereferencing
pointer to incomplete type 'struct _N_VectorContent_Serial'
T1_[0] = nimInt64ToStr((*((struct _N_VectorContent_Serial*)
((*(*v_0Jd0gsgUEmSn2jVcFETIqw.rawVector)).content))).length);
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Run
It seems to complain that it can't find the type 'struct
_N_VectorContent_Serial'. This is the Nim code that is generated for it (I
renamed it to N_VectorContent_Serial_Base in Nim otherwise they would have the
same name.):
N_VectorContent_Serial_Base* {.importc: "struct _N_VectorContent_Serial",
bycopy.} = object
length*: sunindextype
own_data*: cint
data*: ptr realtype
N_VectorContent_Serial* {.impnvector_serial.} = ptr
N_VectorContent_Serial_Base
Run
This original header for this is the file nvector_serial.h which is the one
that is linked to the shared library. There it looks like this:
struct _N_VectorContent_Serial {
sunindextype length; /* vector length */
booleantype own_data; /* data ownership flag */
realtype *data; /* data array */
};
typedef struct _N_VectorContent_Serial *N_VectorContent_Serial;
Run
Method 3:
cImport(inclDir/"sundials/sundials_config.h")
cImport(inclDir/"sundials/sundials_types.h")
cImport(inclDir/"sundials/sundials_nvector.h")
cImport(inclDir/"nvector/nvector_serial2.h")
cImport(inclDir/"nvector/nvector_serial.h", dynlib =
"libsundials_nvecserial")
Run
The way I solved this was by commenting out the type definition in the C header
and copy it to a separate header called nvector_serial2.h which I imported
before the main header. Now the code compiles and runs. I compared the
generated C code before and after my hacky trick and it seems that when I moved
the type definitions to a separate file it was #included in the C code, but
before it was not.
I know this may be a bit hard to follow but the Sundials code base is it as
well :/
Has anyone else had similar experiences or am I just missing something obvious?
