Any Suggestions!

[tmach]

Hello All!
I am using port B interrupt on change to implement a software SPI. I set RB4 as clock and RB5 as latch, data is connected to RB1. I left shift 16 bits of data on a clock L->H and then if I receive Latch L->H trigger, I process the 16-bit data. Of the 16 bits, If bit 0 (the first bit that I receive) is high, I send some configuration data through UART.
To test my code, I send 16 clock pulses and corresponding 16 bits of data (the data changes at -ve edge of clock to avoid any timing issues), then I set latch high. The data that I send is FFFF (first bit is 1) so, I expect to see something from the UART, but I see that the UART works once in 5 or 6 times that I send the data. Also I observe that this freq changes if the latch high pulse width is increased. I am using a clock freq of 2 MHz. But after some time if latch pulse if high for long time, then I see the UART data sent each time I latch the 16-bit data, even if MSB bit is not set! I am clueless
Please advise if I am doing something wrong in my code? My code is attached. My device is 16F874A and 20 MHz osc.

*************************************************************
#INT_RB

void intRB()
{
if(SPI_ENABLE == 0) // shift data if the latch is low
{
if((SPI_CLK == 1) && (WAIT == 0)) //Clock L->H
{
// move two bytes from the DIN line to our (long) word
shift_left(&DIN_data[0],2, SPI_DIN);
}
WAIT = 0;
}
else // enable L->H transition, time to process the shifted data
{
WAIT = 1;

if(bit_test(DIN_data[1],7)) // check for BIT if high
{
BIT_FLG = 1; //set the bit activate flag
}
// start storing the data in the registers

if(bit_test(DIN_data[1],6) && bit_test(DIN_data[1],5))
{
RF.Tx2_L = DIN_data[0];
RF.Tx2_H = DIN_data[1];
}
else if(!bit_test(DIN_data[1],6) && bit_test(DIN_data[1],5))
{
RF.Tx1_L = DIN_data[0];
RF.Tx1_H = DIN_data[1];
}
else if(bit_test(DIN_data[1],6) && !bit_test(DIN_data[1],5))
{
RF.Rx2_L = DIN_data[0];
RF.Rx2_H = DIN_data[1];
}
else if(!bit_test(DIN_data[1],6) && !bit_test(DIN_data[1],5))
{
RF.Rx1_L = DIN_data[0];
RF.Rx1_H = DIN_data[1];
}
}
}


#use delay(clock=20000000)

main()

{
//port initialization

//Interrupt defines

ENABLE_INTERRUPTS(INT_RB);

ENABLE_INTERRUPTS(GLOBAL);

delay_ms(settle); // Let the inputs settle down

while(true)
{

if(BIT_FLG == 1)
{
BIT_FLG = 0;
printf("%2X%2X%2X%2X%2X%2X%2X%2X%2X%2X",
RF.Tx1_H,RF.Tx1_L,RF.Tx2_H,RF.Tx2_L,
RF.Rx1_H,RF.Rx1_L,RF.Rx2_H,RF.Rx2_L);

}
}



}

[Ttelmah]