[C++] vprašanja

Predvsem ti prevajalnik to javi zato, ker je deljenje z ostankom (%) nekako nesmiselno v doublih. Smiselno je namrec le ce imas integerje, se pravi cela stevila, ker pri njih ne mores napisati decimalk, zato dobis nek ostanek pri deljenju. V primeru double in float temu pac ni tako, ker racunalnik vedno izracuna tudi decimalke. Ostanek postane nekoliko nesmiseln, ne?

Stvar je taka, ce delas po modulu ponavadi delas z integerji, double uporabljas ko rabis velik razpon stevl a le na tistih 16 ali koliko ze mest natancno.

/*
 * include/linux/serial.h
 *
 * Copyright © 1992 by Theodore Ts'o.
 *
 * Redistribution of this file is permitted under the terms of the GNU
 * Public License (GPL)
 */

#ifndef _LINUX_SERIAL_H
#define _LINUX_SERIAL_H

#ifdef __KERNEL__
#include <asm/page.h>

/*
 * Counters of the input lines (CTS, DSR, RI, CD) interrupts
 */

struct async_icount {
	__u32	cts, dsr, rng, dcd, tx, rx;
	__u32	frame, parity, overrun, brk;
	__u32	buf_overrun;
};

/*
 * The size of the serial xmit buffer is 1 page, or 4096 bytes
 */
#define SERIAL_XMIT_SIZE PAGE_SIZE

#endif

struct serial_struct {
	int	type;
	int	line;
	unsigned int	port;
	int	irq;
	int	flags;
	int	xmit_fifo_size;
	int	custom_divisor;
	int	baud_base;
	unsigned short	close_delay;
	char	io_type;
	char	reserved_char[1];
	int	hub6;
	unsigned short	closing_wait; /* time to wait before closing */
	unsigned short	closing_wait2; /* no longer used... */
	unsigned char	*iomem_base;
	unsigned short	iomem_reg_shift;
	unsigned int	port_high;
	unsigned long	iomap_base;	/* cookie passed into ioremap */
	int	reserved[1];
};

/*
 * For the close wait times, 0 means wait forever for serial port to
 * flush its output.  65535 means don't wait at all.
 */
#define ASYNC_CLOSING_WAIT_INF	0
#define ASYNC_CLOSING_WAIT_NONE	65535

/*
 * These are the supported serial types.
 */
#define PORT_UNKNOWN	0
#define PORT_8250	1
#define PORT_16450	2
#define PORT_16550	3
#define PORT_16550A	4
#define PORT_CIRRUS     5	/* usurped by cyclades.c */
#define PORT_16650	6
#define PORT_16650V2	7
#define PORT_16750	8
#define PORT_STARTECH	9	/* usurped by cyclades.c */
#define PORT_16C950	10	/* Oxford Semiconductor */
#define PORT_16654	11
#define PORT_16850	12
#define PORT_RSA	13	/* RSA-DV II/S card */
#define PORT_MAX	13

#define SERIAL_IO_PORT	0
#define SERIAL_IO_HUB6	1
#define SERIAL_IO_MEM	2

struct serial_uart_config {
	char	*name;
	int	dfl_xmit_fifo_size;
	int	flags;
};

#define UART_CLEAR_FIFO		0x01
#define UART_USE_FIFO		0x02
#define UART_STARTECH		0x04
#define UART_NATSEMI		0x08

/*
 * Definitions for async_struct (and serial_struct) flags field
 */
#define ASYNC_HUP_NOTIFY 0x0001 /* Notify getty on hangups and closes 
				   on the callout port */
#define ASYNC_FOURPORT  0x0002	/* Set OU1, OUT2 per AST Fourport settings */
#define ASYNC_SAK	0x0004	/* Secure Attention Key (Orange book) */
#define ASYNC_SPLIT_TERMIOS 0x0008 /* Separate termios for dialin/callout */

#define ASYNC_SPD_MASK	0x1030
#define ASYNC_SPD_HI	0x0010	/* Use 56000 instead of 38400 bps */

#define ASYNC_SPD_VHI	0x0020  /* Use 115200 instead of 38400 bps */
#define ASYNC_SPD_CUST	0x0030  /* Use user-specified divisor */

#define ASYNC_SKIP_TEST	0x0040 /* Skip UART test during autoconfiguration */
#define ASYNC_AUTO_IRQ  0x0080 /* Do automatic IRQ during autoconfiguration */
#define ASYNC_SESSION_LOCKOUT 0x0100 /* Lock out cua opens based on session */
#define ASYNC_PGRP_LOCKOUT    0x0200 /* Lock out cua opens based on pgrp */
#define ASYNC_CALLOUT_NOHUP   0x0400 /* Don't do hangups for cua device */

#define ASYNC_HARDPPS_CD	0x0800	/* Call hardpps when CD goes high  */

#define ASYNC_SPD_SHI	0x1000	/* Use 230400 instead of 38400 bps */
#define ASYNC_SPD_WARP	0x1010	/* Use 460800 instead of 38400 bps */

#define ASYNC_LOW_LATENCY 0x2000 /* Request low latency behaviour */

#define ASYNC_BUGGY_UART  0x4000 /* This is a buggy UART, skip some safety
				  * checks.  Note: can be dangerous! */

#define ASYNC_AUTOPROBE	 0x8000 /* Port was autoprobed by PCI or PNP code */

#define ASYNC_FLAGS	0x7FFF	/* Possible legal async flags */
#define ASYNC_USR_MASK	0x3430	/* Legal flags that non-privileged
				 * users can set or reset */

/* Internal flags used only by kernel/chr_drv/serial.c */
#define ASYNC_INITIALIZED	0x80000000 /* Serial port was initialized */
#define ASYNC_CALLOUT_ACTIVE	0x40000000 /* Call out device is active */
#define ASYNC_NORMAL_ACTIVE	0x20000000 /* Normal device is active */
#define ASYNC_BOOT_AUTOCONF	0x10000000 /* Autoconfigure port on bootup */
#define ASYNC_CLOSING		0x08000000 /* Serial port is closing */
#define ASYNC_CTS_FLOW		0x04000000 /* Do CTS flow control */
#define ASYNC_CHECK_CD		0x02000000 /* i.e., CLOCAL */
#define ASYNC_SHARE_IRQ		0x01000000 /* for multifunction cards
					     --- no longer used */
#define ASYNC_CONS_FLOW		0x00800000 /* flow control for console  */

#define ASYNC_BOOT_ONLYMCA	0x00400000 /* Probe only if MCA bus */
#define ASYNC_INTERNAL_FLAGS	0xFFC00000 /* Internal flags */

/*
 * Multiport serial configuration structure --- external structure
 */
struct serial_multiport_struct {
	int		irq;
	int		port1;
	unsigned char	mask1, match1;
	int		port2;
	unsigned char	mask2, match2;
	int		port3;
	unsigned char	mask3, match3;
	int		port4;
	unsigned char	mask4, match4;
	int		port_monitor;
	int	reserved[32];
};

/*
 * Serial input interrupt line counters -- external structure
 * Four lines can interrupt: CTS, DSR, RI, DCD
 */
struct serial_icounter_struct {
	int cts, dsr, rng, dcd;
	int rx, tx;
	int frame, overrun, parity, brk;
	int buf_overrun;
	int reserved[9];
};


#ifdef __KERNEL__
/* Export to allow PCMCIA to use this - Dave Hinds */
extern int register_serial(struct serial_struct *req);
extern void unregister_serial(int line);

/* Allow architectures to override entries in serial8250_ports[] at run time: */
struct uart_port;	/* forward declaration */
extern int early_serial_setup(struct uart_port *port);

#endif /* __KERNEL__ */
#endif /* _LINUX_SERIAL_H */

To je koda, ki sem jo nasel v linux/serial.h in me zanima če je to datoteka, katera omogoča pošiljanje podatkov na seijski port - če se ne motim, če se motim me popravte.

lp

"UNIX & C++"

Kako pa so delovale com miške v linuxu ?
Ta link koliko sem ga razumel omogoča povezavo z seriskim portom in pošiljanjem - če se motim me popravite.

lp

UNIX & C++

To bi naj bilo to samo to je bolj razlaga.

lp

"UNIX & C++"

Verjetno so tudi bolj prefinjeni pristopi, ampak če imaš dostop do osciloskopa je zelo zanimivo opazovati, kaj se dogaja.

Pravzaprav lahko v ta namen uporabiš kar zvočno kartico.

Kaj pa tole: http://xoscope.sourceforge.net/
http://www.linuxnetmag.com/en/issue4/m4oszillo1.html

void stevilo1()
{}

void stevilo2()
{}

void stevilo3()
{}

int main()
{
  stevilo1();
  stevilo2();
  stevilo3();
  return 0;
}

lp

"UNIX & C++"

Stavek goto omogoča skok na poljubno vrstico v programu oziroma na splošen stavek z oznako. Takšno krmiljenje programa ni v skladu s strukturiranim programiranjem, zato se stavka goto izogibljamo.

sintaksa stavka goto je preprosta : goto oznaka.

lp

"UNIX & C++"

A ima C++ kaj od tega, večina sem našel samo zaokrožitev in za FIX ukaz nisem našel nič primernega.

lp

"UNIX & C++"

int main()
{
  double dolzina, sirina;

  std::string MyLokator;

    std::cout << " Vnesi lokator: ";
    getline(std::cin, MyLokator);

    dolzina = (MyLokator[0] - 65)*20 - 180 + (MyLokator[2] - 0x30)*2 + (MyLokator[4] - 65)/12;
    sirina =  (MyLokator[1] - 65)*10 - 90 + (MyLokator[3] - 0x30) + (MyLokator[5] - 65)/24;

    std::cout << " Geo. dolzina : " << dolzina << std::endl
              << " Geo. sirina  : " << sirina << std::endl;
return 0;
}

Zakaj mi program gre obe vrednosti pretvori v celo število. Če uporabim za MyLokator[x] - y uporabim posamezno spremenljivko potem mi vrne decimalni zapis drugače izpiše celo število. V čem je problem ali naj uporabin 6 sprmenljivk ali moram kaj popraviti?
Vnesite JN76KM in vam mora program vrniti (za pravilni izračuna - preverjeno):
Geo. dolzina : 14.8333
Geo. sirina : 46.5

lp

"UNIX & C++"

   d0 = MyLokator[0] - 65;
    d2 = MyLokator[2] - 0x30;
    d4 = MyLokator[4] - 65;
    s1 = MyLokator[1] - 65;
    s3 = MyLokator[3] - 0x30;
    s5 = MyLokator[5] - 65;

Torej tako mora biti ?

lp

"UNIX & C++"

(MyLokator[4] - 65)/12.0;

Pozor pri 12.0, to pomeni da delis z double in ne z int ter zato dobis rezultat kot double in ne int

Poskusi pa boš videl. Samo ne vidim razloga da bi uporabljal to knjižnico.

A ne najdeš nobenega tutoriala na to temo (narejenega za linux)?

v najslabsem primeru si poglej izvorno kodo minicoma

Pa saj ne more biti tako grozno. Priklopi dva računalnika s serijskim null modem kablom in na enem prižgi minicom. Potem se lahko na drugem igraš s svojim programčkom, pa boš točno videl kakšen je rezultat.

http://alioth.debian.org/projects/minicom

Malo bolj podrobno... :P

Aja, taka komunikacija... :P

Verjetno nimas pravic na /dev/ttyS* vratih.. preveri.

Ce je kabel dober, potem bi ze echo "lalala" > /dev/ttyS? moral izpisati na win masini.

Ce se ne, potem je nekaj narobe nastavljeno.

Poskusi s temle: http://realterm.sourceforge.net/
Dokler ti komunikacija po serijskem kablu ne steče sploh ne poskušaj popravljati kode. Če tipkaš v minicom moraš videti besedilo v realtermu / hyper terminalu in obratno.

Preberi so kaj o socketih. Na voljo imaš sistemske knjiižnice in malenkost višje-nivojske, če hočeš da ti program deluje na več platformah.

Prišteješ 0,5 in uporabiš ceil().

In kaka je razlika med double ceil(double) in double floor(double)?

lp

"UNIX & C++"

ceil je zaokroževanje navzgor, floor pa navzdol - tako kot si spraševal.

edit: nisem opazil da je že bilo odgovorjeno.