reactos/lib/crtdll/old cruft/stdlib/alloca.c

   1 #include <precomp.h>
   2 #include <msvcrt/stdlib.h>
   3
   4
   5 #undef alloca
   6 void *alloca(size_t s)
   7 {
   8         register unsigned int as = s;
   9
  10 // alloca(0) should not return the stack pointer
  11         if ( s == 0 )
  12                 return NULL;
  13
  14         as = (as + 3) & (~3);
  15
  16         __asm__ __volatile__(
  17         "mov %0, %%edx          \n"
  18 //      "popl %%ebp             \n"
  19         "leave                  \n"
  20         "popl  %%ecx            \n"
  21         "subl  %%edx, %%esp     \n"
  22         "movl  %%esp, %%eax     \n"
  23         "addl  $20, %%eax        \n"//4 bytes + 16 bytes = arguments
  24         "push  %%ecx            \n"
  25         "ret                    \n"
  26         :
  27         :"g" ( as)
  28         );
  29
  30
  31         return NULL;
  32 }
  33
  34 void *_alloca(size_t s)
  35 {
  36         register unsigned int as = s;
  37
  38 // alloca(0) should not return the stack pointer
  39         if ( s == 0 )
  40                 return NULL;
  41
  42
  43         if ( (s & 0xfffffffc)  != 0 )
  44                 as += 4;
  45
  46         as &= 0xfffffffc;
  47
  48         __asm__ __volatile__(
  49         "mov %0, %%edx          \n"
  50 //      "popl %%ebp             \n"
  51         "leave                  \n"
  52         "popl  %%ecx            \n"
  53         "subl  %%edx, %%esp     \n"
  54         "movl  %%esp, %%eax     \n"
  55         "addl  $20, %%eax        \n"//4 bytes + 16 bytes = arguments
  56         "push  %%ecx            \n"
  57         "ret                    \n"
  58         :
  59         :"g" ( as)
  60         );
  61
  62
  63         return NULL;
  64 }