C++ DROP函數代碼示例

void tcsipcall_hangup(struct tcsipcall*call) {
    if(call->sess) call->sess = mem_deref(call->sess);

    if(!call->reason && (call->cstate & CSTATE_EST)==CSTATE_EST)
        call->reason = CEND_OK;

    if(!call->reason && (call->cstate & CSTATE_EST)==0)
        call->reason = CEND_HANG;

    DROP(call->cstate, CSTATE_ALIVE);
    DROP(call->cstate, CSTATE_EST);
    /*
     * Call terminated
     * Remote party dropped something heavy
     * on red button
     * */

    if(call->media) {
        tcmedia_stop(call->media);
        call->media = mem_deref(call->media);
    }

    call->handler(call, call->handler_arg);
    tcsipcall_remove(call);
    mem_deref(call);
}

int main()
{
    START_MACHINE;
    JUMP(CONTINUE);

#include "char.lib"
#include "io.lib"
#include "math.lib"
#include "string.lib"
#include "system.lib"
#include "scheme.lib"

 CONTINUE:
    /* initialize the 4 singletons */
    PUSH(IMM(1));
    CALL(MAKE_SOB_BOOL);         /* define SOB_BOOL_TRUE in mem[1]*/
    DROP(1);
    PUSH(IMM(0));
    CALL(MAKE_SOB_BOOL);         /* define SOB_BOOL_FALSE in mem[3]*/
    DROP(1);
    CALL(MAKE_SOB_NIL);          /* define nil in mem[5] */
    CALL(MAKE_SOB_VOID);         /* define #Void in mem[6] */

  /* start of code */
  /* CALL(MAKE_SOB_NIL); */
    /* MOV(R0, IND(IMM(4))); */
    MOV(R0, IMM(5));
  PUSH(R0);
  CALL(IS_SOB_TRUE);
  CMP(R0, IMM(1));              /* 1 means R0 was true, 0 means it
                                   was #f */
  JUMP_EQ(Lelse1);
  PUSH(IMM(1));
  CALL(MAKE_SOB_BOOL);
  JUMP(Lexit1);
 Lelse1:
  PUSH(IMM(0));
  CALL(MAKE_SOB_BOOL);
 Lexit1:

  PUSH(R0);
  CALL(WRITE_SOB);
  /* newline and stop machine */
  PUSH(IMM('\n'));
  CALL(PUTCHAR);
  STOP_MACHINE;

  return 0;
}

/*
 - p_bre - BRE parser top level, anchoring and concatenation
 * Giving end1 as OUT essentially eliminates the end1/end2 check.
 *
 * This implementation is a bit of a kludge, in that a trailing $ is first
 * taken as an ordinary character and then revised to be an anchor.  The
 * only undesirable side effect is that '$' gets included as a character
 * category in such cases.  This is fairly harmless; not worth fixing.
 * The amount of lookahead needed to avoid this kludge is excessive.
 */
static void
p_bre(struct parse *p,
    int end1,		/* first terminating character */
    int end2)		/* second terminating character */
{
	sopno start = HERE();
	int first = 1;			/* first subexpression? */
	int wasdollar = 0;

	if (EAT('^')) {
		EMIT(OBOL, 0);
		p->g->iflags |= USEBOL;
		p->g->nbol++;
	}
	while (MORE() && !SEETWO(end1, end2)) {
		wasdollar = p_simp_re(p, first);
		first = 0;
	}
	if (wasdollar) {	/* oops, that was a trailing anchor */
		DROP(1);
		EMIT(OEOL, 0);
		p->g->iflags |= USEEOL;
		p->g->neol++;
	}

	REQUIRE(HERE() != start, REG_EMPTY);	/* require nonempty */
}

/* find  ( a u chain - a u 0 | code -1) */
void mu_find()
{
    char *token = (char *) ST2;
    cell length = ST1;
    struct dict_entry *pde = (struct dict_entry *)TOP;

    /*
     * Only search if length < 128. This prevents us from matching hidden
     * entries!
     */
    if (length < 128)
    {
        while ((pde = (struct dict_entry *)pde->n.link) != NULL)
        {
            /* for speed, don't test anything else unless lengths match */
            if (pde->n.length != length) continue;

            /* lengths match - compare strings */
            if ((*match)(pde->n.suffix + SUFFIX_LEN - length, token, length) != 0)
                continue;

            /* found: drop token, push code address and true flag */
            DROP(1);
            ST1 = (addr)&pde->code;
            TOP = -1;
            return;
        }
    }
    /* not found: leave token, push false */
    TOP = 0;
}

/* (name)  ( link a u hidden - 'suffix) */
void mu_name_()
{
    struct dict_name *pnm = new_name(
        (struct dict_name *)ST3, (char *)ST2, ST1, TOP);
    DROP(3);
    TOP = (addr)pnm;
}

/*
 * usb-find-device (vendor-id product-id -- handle -1 | 0)
 */
void mu_usb_find_device()
{
    int matched;

    /* Enumerate USB device tree, looking for a match */
    matched = enumerate_devices(ST1, TOP);

    /*
     * enumerate_devices only returns failure (-1) if it found a match but
     * couldn't open the device for read & write. Tell the user about the
     * error.
     */
    if (matched < 0) return abort_strerror();

    if (matched == 0)
    {
        /* No match found */
        DROP(1);
        TOP = 0;
    }
    else
    {
        /* Matched; return the device's _open_ file descriptor */
        ST1 = matched;
        TOP = -1;
    }
}

/*
 * usb-control (bmRequestType bRequest wValue wIndex wLength 'buffer device - count)
 */
void mu_usb_control()
{
    struct usb_ctl_request ucr;
    int fd;

#define req ucr.ucr_request
    req.bmRequestType = SP[6];
    req.bRequest = SP[5];
    USETW(req.wValue, SP[4]);
    USETW(req.wIndex, ST3);
    USETW(req.wLength, ST2);
    ucr.ucr_data = (void *)ST1;
    ucr.ucr_addr = 0;
    ucr.ucr_flags = (req.bmRequestType == UT_READ_DEVICE)
                    ? USBD_SHORT_XFER_OK : 0;
    fd = TOP;
    DROP(6);

    if (ioctl(fd, USB_DO_REQUEST, &ucr) == -1)
    {
        TOP = 0;    /* count of bytes transferred */
        return abort_strerror();
    }
    TOP = ucr.ucr_actlen;   /* actual length transferred */
}

/*
 * mu_read_file mmaps the file and returns its contents as a string
 */
void mu_read_file()     /* fd - addr len */
{
    char *p = NULL;
    struct stat s;
    int fd;

    fd = TOP;

    if (fstat(fd, &s) == -1)
    {
        close(fd);
        return abort_strerror();
    }

    /* If size of file is zero, don't try to mmap; it will fail and error
     * out. Instead, simply return a buffer starting at address 0, of
     * length 0.
     */
    if (s.st_size != 0)
    {
        p = (char *) mmap(0, s.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
        if (p == MAP_FAILED)
        {
            close(fd);
            return abort_strerror();
        }
    }

    DROP(-1);
    ST1 = (addr) p;
    TOP = s.st_size;
}

void mu_interpret()
{
    source.start = (char *)ST1;
    source.end =   (char *)ST1 + TOP;
    DROP(2);

    first = source.start;

    for (;;)
    {
        mu_token();
        if (TOP == 0) break;
        consume();
        mu_qstack();
    }
    DROP(2);
}

void mu_close_file()
{
    while (close(TOP) == -1)
    {
        if (errno == EINTR) continue;
        return abort_strerror();
    }
    DROP(1);
}

int main()
{
  START_MACHINE;

  JUMP(CONTINUE);

#include "char.lib"
#include "io.lib"
#include "math.lib"
#include "string.lib"
#include "system.lib"
#include "scheme.lib"

 CONTINUE:
  PUSH(IMM(64));
  CALL(MALLOC);
  SHOW("MALLOC RETURNED ", R0);
  DROP(1);
  PUSH(R0);
  OUT(IMM(2), IMM('?'));
  OUT(IMM(2), IMM(' '));
  CALL(READLINE);
  SHOW("READ IN STRING AT ADDRESS ", R0);
  PUSH(R0);
  CALL(STRING_TO_NUMBER);
  DROP(1);
  SHOW("READ IN ", R0);
  MUL(R0, R0);
  SHOW("SQUARE IS ", R0);
  PUSH(R0);
  CALL(NUMBER_TO_STRING);
  DROP(1);
  PUSH(R0);
  SHOW("STR[0] = ", INDD(R0, 0));
  SHOW("STR[1] = ", INDD(R1, 0));
  SHOW("STR[2] = ", INDD(R2, 0));
  SHOW("STR[3] = ", INDD(R3, 0));
  CALL(WRITELN);
  DROP(1);

  STOP_MACHINE;

  return 0;
}

/*
 * This version of interpret is -not- exported to Forth! We are going to
 * re-define it in Forth so it executes as "pure" Forth, and we can use
 * Forth-side, return-stack-based exception handling!
 *
 * Oddly enough, the Forth implementation will be be *exactly* the same!
 * The only difference is that it will be executing in Forth, so we can use
 * R stack tricks to change its behaviour.
 */
static void muboot_interpret()
{
    for (;;)
    {
        mu_token();
        if (TOP == 0) break;
        mu_consume();
        muboot_show_stack();
    }
    DROP(2);
}

/* time and date */
static void push_forth_time_from_libc_time (struct tm *ptm, char *tz)
{
    DROP(-8);
    TOP = strlen (tz);
    ST1 = (addr) tz;
    ST2 = ptm->tm_sec;
    ST3 = ptm->tm_min;
    SP[4] = ptm->tm_hour;
    SP[5] = ptm->tm_yday;     /* 0 to 365 */
    SP[6] = ptm->tm_mday;
    SP[7] = ptm->tm_mon;      /* 0 to 11 */
    SP[8] = ptm->tm_year + 1900;
}

/*
 * We need a way to do short sleeps for talking to sensitive hardware
 * targets (like the Freescale HC908 series). I'm not getting good data
 * from the bootloader, and wondering if some short pauses would help.
 */
void mu_nanosleep()
{
    struct timespec ts;

    ts.tv_sec = ST1;
    ts.tv_nsec = TOP;

    while (nanosleep(&ts, &ts) == -1)
    {
        if (errno == EINTR) continue;
        return abort_strerror();
    }
    DROP(2);
}

void ZBRANCH()
{
    SWAP();

    if (pop(PSP) == 0)
    {
        BRANCH();
    }

    else
    {
	DROP();
    }
}