/* Create a new process with a given address as the entry point.  MUST be
 * called from a process (not a plain task). */

#include <stdio.h>
#include <exec/tasks.h>
#include <dos/dosextens.h>
#include <dos/dostags.h>
#include <proto/exec.h>
#include <proto/dos.h>

long fork_stacksize = 0;	/* what stack size to use; 0 = from parent */


#define myproc ((struct Process *)mytask)
#define pproc ((struct Process *)parent)

/* forkproc() entry point */
static __geta4 void fork_entry()
{
    struct Task *mytask = FindTask(NULL), *parent;
    __stkargs void (*entry)(void *);
    void *entrydata;
    char *s;
    int i;
    long ptr;

    s = mytask->tc_Node.ln_Name; ptr = 0;
    for (i = 0; i < 8; ++i) {
	ptr = (ptr<<4) | (*s++ & 0x0F);
    }
    parent = (struct Task *)ptr;
    mytask->tc_Node.ln_Name = parent->tc_Node.ln_Name;
    entrydata = (void *)myproc->pr_ConsoleTask;
    myproc->pr_ConsoleTask = pproc->pr_ConsoleTask;
    entry = (void (*)())myproc->pr_WindowPtr;
    myproc->pr_WindowPtr = pproc->pr_WindowPtr;
    entry(entrydata);
}

#undef myproc
#undef pproc


struct Process *forkproc(__stkargs void (*entry)(void *), void *entrydata)
{
    long tags[] = {
	NP_Entry, (long)fork_entry,
	NP_Input, 0,
	NP_Output, 0,
	NP_Error, 0,
	NP_CloseInput, FALSE,
	NP_CloseOutput, FALSE,
	NP_CloseError, FALSE,
	NP_StackSize, 0,
	NP_Name, 0,		/* pass our TCB here */
	NP_WindowPtr, 0,	/* pass entry point here */
	NP_ConsoleTask, 0,	/* pass entry data here */
	NP_Cli, FALSE,
	TAG_END
    };
    struct Task *mytask = FindTask(NULL);
    char s[9];
    int i;
    long ptr;

    tags[1] = (long)fork_entry;
    tags[3] = fdtofh(fileno(stdin));
    tags[5] = fdtofh(fileno(stdout));
    tags[7] = fdtofh(fileno(stderr));
    if (fork_stacksize)
	tags[15] = fork_stacksize;
    else
	tags[15] = mytask->tc_SPUpper - mytask->tc_SPLower;
    ptr = (long)mytask;
    for (i = 0; i < 8; ++i) {
	s[i] = ((mytask >> 28) & 0x0F) | 0x30;
	mytask <<= 4;
    }
    s[8] = 0;
    tags[17] = (long)s;		/* have to do this in a roundabout way
				 *    because CreateNewProc() makes a copy
				 *    of the title string */
    tags[19] = (long)entry;
    tags[21] = (long)entrydata;
    return CreateNewProc(tags);
}