/*
   thread.c -- linux threading support
   (stolen mostly from one of linus' posts on linux-kernel)
*/

#include <stdio.h>
#include <signal.h>
#include <stdlib.h>
#include <fcntl.h>
#include <asm/unistd.h>

/* flags to use when creating a new thread */
#define CSIGNAL         0x000000ff    /* signal mask sent at exit */
#define CLONE_MEM       0x00000100    /* set to share memory */
#define CLONE_FS        0x00000200    /* set to share "fs info" (?) */
#define CLONE_FILES     0x00000400    /* set to share open files */
#define CLONE_SIGHAND   0x00000800    /* set to share signal handlers */

typedef void (*clonefunc)(void *);

/* create a new thread -- returns pid or -1 on error */
int new_thread(fn,data,flags,stacksize)
clonefunc fn; void *data; unsigned int stacksize,flags;
{
  long retval; void **newstack;
  /* make the new stack: */
  newstack=(void **)nmalloc(stacksize);
  if (!newstack) return (-1);
  /* rearrange pointer so it's at the other end of the memory block */
  newstack=(void **)(stacksize+(char *)newstack);
  /* put the (void *)data on the new stack */
  *--newstack=data;
  /* now linus does some assembly in this weird psued-language i have */
  /* no clue about... sheesh. */
  __asm__ __volatile__(
    "int $0x80\n\t"
    "testl %0,%0\n\t"
    "jne 1f\n\t"
    "call *%3\n\t"
    "movl %2,%0\n\t"
    "int $0x80\n"
    "1:\t"
    :"=a" (retval)
    :"0" (__NR_clone),"i" (__NR_exit),
     "r" (fn),"b" (flags|SIGCHLD),"c" (newstack));
  if (retval<0) {
    errno=(-retval);
    retval=(-1);
  }
  return retval;
}