From:	qballlives AT aol DOT com (QBallLives)
Newsgroups:	comp.os.msdos.djgpp
Subject:	Modem to modem - what's wrong w/ my ISR
Lines:	126
Message-ID:	<1998052200481600.UAA20955@ladder03.news.aol.com>
NNTP-Posting-Host:	ladder03.news.aol.com
Date:	22 May 1998 00:48:16 GMT
Organization:	AOL http://www.aol.com
To:	djgpp AT delorie DOT com
DJ-Gateway:	from newsgroup comp.os.msdos.djgpp

I've been working on porting some code from Chapter 9 of the Black Art of 3D
game programming to djgpp...

I've managed to make calls and wait for calls... but I'm getting Sigsev after a
few seconds.... I'm thinking my ISR or it's installation might be at fault.... 

Here's the ISR code, and the installation of it:

void Serial_ISR(void)
{
// this is the serial ISR that is installed. It is called whenever a character
// is received. The received character is then placed into the next position
// in the input ring buffer

//asm("cli; pusha");

asm("sti");

serial_ch = inportb(open_port + SERIAL_RBF);

// wrap buffer index around

if (!serial_ch)
{
    // restore PIC

    outportb(PIC_ICR,0x20);
    return;
} // end if no character

if (++serial_end > SERIAL_BUFF_SIZE-1)
    serial_end = 0;

// move character into buffer

serial_buffer[serial_end] = serial_ch;

++char_ready;

// restore PIC

outportb(PIC_ICR,0x20);

//asm("popa; sti");
} // end Serial_ISR

int Serial_Open(int port_base, int baud, int configuration)
{

// this function will open up the serial port, set it's configuration, turn
// on all the little flags and bits to make interrupts happen and load the
// ISR

unsigned char data;

// save the port I/O address for other functions

open_port = port_base;

// first set the baud rate

// turn on divisor latch registers

outportb(port_base + SERIAL_LCR, SERIAL_DIV_LATCH_ON);

// send low and high bytes to divsor latches

outportb(port_base + SERIAL_DLL, baud);
outportb(port_base + SERIAL_DLH, 0);

// set the configuration for the port

outportb(port_base + SERIAL_LCR, configuration);

// enable the interrupts

data = inportb(port_base + SERIAL_MCR);
data = SET_BITS(data,SERIAL_GP02);
outportb(port_base + SERIAL_MCR, data);

outportb(port_base + SERIAL_IER, 1);

// hold off on enabling PIC until we have the ISR installed


if (port_base == COM_1)
   {
    New_Serial_ISR.pm_offset   = (int)Serial_ISR;
    New_Serial_ISR.pm_selector = _go32_my_cs();
    _go32_dpmi_get_protected_mode_interrupt_vector(INT_SERIAL_PORT_0,
&Old_Serial_ISR);
    _go32_dpmi_allocate_iret_wrapper(&New_Serial_ISR);
    _go32_dpmi_set_protected_mode_interrupt_vector(INT_SERIAL_PORT_0,&New_
Serial_ISR);

   }
else
   {
    New_Serial_ISR.pm_offset   = (int)Serial_ISR;
    New_Serial_ISR.pm_selector = _go32_my_cs();
    _go32_dpmi_get_protected_mode_interrupt_vector(INT_SERIAL_PORT_1,
&Old_Serial_ISR);
    _go32_dpmi_allocate_iret_wrapper(&New_Serial_ISR);
    _go32_dpmi_set_protected_mode_interrupt_vector(INT_SERIAL_PORT_1,&New_
Serial_ISR);
   }

// enable the recieve character interrupt on PIC for selected comm port

old_int_mask = inportw(PIC_IMR);

outportb(PIC_IMR, (port_base==COM_1) ? (old_int_mask & 0xEF) : (old_int_mask &
0xF7 ));

return(1);

} // Serial_Open


Any help would be appreciated....


Jim the loiterer
aloiterer AT juno DOT com
http://members.xoom.com/JimMcCue/index.htm
(Jim the loiterer's PC games, programming, & stuff...)

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