utility.c

以ST公司CPU为核心的彩色电视机的完整源程序。

/********************** SGS-THOMSON MICROELECTRONICS ************************
FILENAME     : UTILITY.C
VERSION      : V1.0
DATE         : JAN 1999
AUTHOR(s)    : ASHISH RUDOLA / DEEPAK DOSHI
PROCESSOR    : ST92195
DESCRIPTION  : This file contains the source code for the user utilities.
MODIFICATIONS:
	-
*****************************************************************************/
#include "macro.h"
#include "utility.h"
#include "tv_glob.h"
#include "register.h"
/*****************************************************************************
INPUTS     : Number of microseconds to wait for
OUTPUTS    : none
DESCRIPTION: This function generates a "n" microseconds delay.
             Keep this function in assembler to control processing time.

             Internal clock frequency = 24Mhz ( 1 INT = 1/24MHZ )
         call: 12 INT clock cycles => 0.5us 
         sub:  6  INT clock cycles => 0.25us 
   	     jrnz: 6  INT clock cycles => 0.25us  
         nop:  2  INT clock cycles =>  
   	     ret:  8  INT clock cycles (internal stack) =>  
         dec:  4  INT clock cycles => 
Equation is
===========
        Xus = (microsecond_counter+1) us 
        2 < Xus < 256
where us_count is the count generated by the macro
to obtain the delay of Xus

e.g: if for a Xus=10us delay us_count (microsecond counter) must be 9

*****************************************************************************/
void us_delay(void)
{
	asm volatile ("
MD0:	            dec %0
                        nop
                        nop
                        nop
                        nop
                        nop
                        nop
                        
                        nop
	               jpnz MD0
	                    nop
	                    nop" : "=R"(microsecond_counter) :);
}

/*****************************************************************************
INPUTS     : Number of milliseconds to wait for
OUTPUTS    : none
DESCRIPTION: This function generates a "n" milliseconds delay.
             Keep this function in assembler to control processing time.
*****************************************************************************/

void ms_delay(void)
{
	microsecond_delay(250);
	microsecond_delay(250);
	microsecond_delay(250);
	microsecond_delay(240);
	asm volatile ("sub %0,#1
                       jpnz ms_delay" : "=R"(millisecond_counter) :);
}

/*****************************************************************************
INPUTS     : value - Parameter to process
             mask - Value (within parameter) to keep and to shift
OUTPUTS    : result
DESCRIPTION: This function outputs the requested value shifted to the right.
*****************************************************************************/
unsigned int  get_value(unsigned int  value, unsigned int  mask)
{

	value = value & mask;
	while (!(mask & 0x01))
	{
		mask = mask >> 1;
		value = value >> 1;
	}
	return value;
}

/*****************************************************************************
INPUTS     : value - Parameter to process
             mask - Value (within parameter) to keep and to shift
OUTPUTS    : result
DESCRIPTION: This function outputs the requested value shifted to the left.
*****************************************************************************/

unsigned int  set_value(unsigned int  value, unsigned int  mask)
{
	unsigned int i;			/* Temporary storage */
	i =0;
	while (!(mask & 0x01))
	{
		mask = mask >> 1;
		i++;;
	}
	value = value << i;
	return value;
}

/*****************************************************************************
INPUTS     : 
OUTPUTS    : 
DESCRIPTION: 
*****************************************************************************/

unsigned int roll_inc(unsigned int value,unsigned int maximum_value)
{
	value++;
	if (value>maximum_value)
	 	value = 0;
	return value;
}


/*****************************************************************************/

unsigned int roll_source(unsigned int value,unsigned int maximum_value)
{
	value++;
	#ifndef OPTION_AV2
		if(value == 2)
			value++;
	#endif

	#ifndef OPTION_SVHS
		if(value == 3)
			value++;
	#endif

	#ifndef OPTION_RGB
		if(value == 4)
			value++;
	#endif

	if (value>maximum_value)
	 	value = 0;
	return value;
}

/*****************************************************************************
INPUTS     : 
OUTPUTS    : 
DESCRIPTION: 
*****************************************************************************/

unsigned int roll_dec(unsigned int value,unsigned int maximum_value)
{
	value--;
	if (value ==0xffff)
	 	value = maximum_value;
	return value;
}