a basic test of c module

ruby

try to load .dll using .h header to supply definition signature

t.c

#include <stdio.h>

__declspec(dllexport) short add(short a, short b) {
  return a + b;
}


__declspec(dllexport) long long sub(long long a, long long b) {
  return a - b;
}

t.h

short
add(short a, short b) ;


long
long
sub
(long long
    a,
    long long b) ;

simple module crequire.lua:

t = {}
t['unsigned long long'] = 'L'
t['const wchar_t*'] = 'W'
t['unsigned short'] = 'S'
t['unsigned char'] = 'C'
t['unsigned long'] = 'J'
t['unsigned int'] = 'I'
t['const char*'] = 'Z'
t['long long'] = 'l'
t['uint32_t'] = 'I'
t['uint64_t'] = 'L'
t['wchar_t*'] = 'W'
t['uint16_t'] = 'S'
t['int16_t'] = 's'
t['int32_t'] = 'i'
t['int64_t'] = 'l'
t['double'] = 'd'
t['size_t'] = '#'
t['struct'] = '.'
t['char*'] = 'Z'
t['float'] = 'f'
t['short'] = 's'
t['union'] = 'u'
t['void*'] = 'p'
t['bool'] = 'B'
t['char'] = 'c'
t['long'] = 'j'
t['int'] = 'i'

trev = {}
for k,v in pairs(t) do
  trev[v] = trev[v] and (trev[v]..', or '..k)  or k
end


torder = {}
for k in pairs(t) do table.insert(torder,k) end
table.sort(torder, function(a,b) return #a>#b end)


function getdef(header, name)
   header = header:gsub('%s+', ' ')  -- also remove comment?
   wordboundary = '%f[_%w]'
   bracket = '%s-%b()'
   a,b = header:find(wordboundary..name..bracket)
   c = getbegin(header, b)
   returndef = header:sub(c, a-1) print('returndef', returndef)
   returntype = gettype(returndef)
   d = header:find('%(', a)
   arguments = header:sub(d+1, b-1)..','
   prev=0
   argutypest = {}
   for e in arguments:gmatch('(),') do
      argu = arguments:sub(prev+1, e)
      argut = gettype(argu)
      print(argu, argut)
      argutypest[#argutypest+1] = gettype(argu)
      prev=e
   end
   argutypes = table.concat(argutypest)
   return '('..argutypes..')'..returntype
end


function gettype(s)
   for _,k in ipairs(torder) do
      if s:find(k) then return t[k] end
   end
   return ''
end


function getbegin(s, b)
   -- begin at ;
   for i = b-1,1,-1 do
   if s:sub(i,i)==';' then b=i+1 break end end
   if b>a then b=1 end
   return b
end


function describe(s)
   local a,b = s:find('%b()')
   print'arguments:'
   if b-a==1 then print'  none'
   else for i=1,b-a-1 do print('',i,trev[s:sub(a+i,a+i)]) end end
   print'returns:'
   if b==#s then print'  none'
   else print('',trev[s:sub(#s)]) end
end


function crequire(dllname, funcname)
   mylib = cmodule.Library(dllname..'.dll')
   header = io.open(dllname..'.h'):read'a'
   def = getdef(header, funcname)
   mylib[funcname] = def
   print(funcname, def)
   describe(def)
   return mylib[funcname]
end

cmodule = require'c'
return crequire

and test in quickrt:

╭━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━╮
│ QuickRT - Powerful REPL for LuaRT  │
│ Copyright © 2025, Samir Tine       │
╰━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━╯

► crequire = require'crequire'

► add = crequire('t', 'add')
returndef       short
short a,        s
 short b,       s
add     (ss)s
arguments:
        1       int16_t, or short
        2       int16_t, or short
returns:
        int16_t, or short

► sub = crequire('t', 'sub')
returndef        long long
long long a,    l
 long long b,   l
sub     (ll)l
arguments:
        1       long long, or int64_t
        2       long long, or int64_t
returns:
        long long, or int64_t

► add(5,4)
9

► sub(5,4)
1

► sub(4,5)
4294967295

► c=require'c'
► c.longlong(sub(4,5)):tonumber()
0

► c.longlong(sub(5,4)):tonumber()
0

question,

uint32_t I or J ?
int32_t i or j ?
int B or i ?
or both are ok ?

is # size_t ?

I trid to set function return value to size_t, #
but it seems like # is not recognized

add(4,5)
>>> Unknown '#' signature character

and obviously difficulty lies in struct and union etc complcate types

Samir

Ok, here are some answers :

ruby uint32_t I or J ?
int32_t i or j ?
int B or i ?
or both are ok ?

It depends on the current _ARCH (for example on x64, "i" is a 64 bits integer and a 32 bits one on x86)

ruby is # size_t ?

I trid to set function return value to size_t, #
but it seems like # is not recognized

Yes, # is for size_t, but sadly, size_t return value is not yet implemented (I just forgot it in fact !)

Samir

There is a lot of bugs reported here.
Let me the time to investigate this.

Samir

Update : # returns values are now implemented

ruby

I translated this simple .c into .lua:

#include "raylib.h"
int main(void)
{
    const int width = 800;
    const int height = 600;
    const char* title = "hello world";
    
    InitWindow(width, height, title);
    
    while (!WindowShouldClose()) //   wait press Esc to close window
    {   BeginDrawing();
        EndDrawing();
    }
    CloseWindow(); 
    return 0;
}

and .lua

c = require'c'
r = c.Library'raylib.dll'

r.InitWindow = '(iiZ)'
r.WindowShouldClose = '()B'
r.BeginDrawing = '()'
r.EndDrawing = '()'
r.CloseWindow = '()'

width = 800
height = 610
title = 'hello world' 
r.InitWindow(width, height, title)

while not r.WindowShouldClose() do -- wait press Esc to close window
   r.BeginDrawing()
   r.EndDrawing()
end

r.CloseWindow()

print'end'

this works, it create a blank window with specified size.

> luart1.91.exe raylib.lua
INFO: Initializing raylib 5.5
INFO: Platform backend: DESKTOP (GLFW)
...
INFO: DISPLAY: Device initialized successfully
INFO:     > Display size: 1920 x 1200
INFO:     > Screen size:  800 x 610
...
INFO: PLATFORM: DESKTOP (GLFW - Win32): Initialized successfully
...
INFO: Window closed successfully
end

it has a detailed .lua file for every function signature exported, maybe need an automatic function generator to do this automatically

ruby

for example on x64, "i" is a 64 bits integer and a 32 bits one on x86

from doc: [Login to see the link]

character 	argument type
B 	int (or bool for C++)
i 	int / int32_t
I 	unsigned int / uint32_t
j 	long / int32_t
J 	unsigned long / uint32_t
l 	long long / int64_t

still not clear.

in my x64, "i" is a 64 bits integer, so int should be l ?

can you make it clear that in most x64 which type is to which type.

the slash / is confusing.

maybe the slash has a 64bits/32bits convention?

Samir

I agree, the slash is totally confusing.
I will fix the documentation