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The C Users' Group Library 1994 August
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wc-cdrom-cusersgrouplibrary-1994-08.iso
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vol_100
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108_01
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datedemo.c
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1985-11-14
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#include CLOCK.H
#define BASE_YEAR 1978
/* Example program for Mountain Hardware "100,000 day clock" S-100 board.
This main program simply calls the date function and time function,
displaying the returned strings. */
main()
{
char date_str[35]; /* string (character array) for date */
char time_str[8]; /* string for time */
if (date(date_str,0)){
printf("Exiting to CP/M\07\n");
exit();
}
printf("Demonstration of 'C' functions for the ");
printf("Mountain Hardware 100,000 day clock.\n\n");
printf("\tBy Bill Bolton, Software Tools\n");
printf("\tP.O. Box 80,\n\tNewport Beach,\n");
printf("\tNSW, 2106, AUSTRALIA\n\n");
printf("\Date format 0 is %s\n\n",date_str);
date(date_str,1);
printf("Date format 1 is %s\n\n",date_str);
date(date_str,2);
printf("Date format 2 is %s\n\n",date_str);
date(date_str,3);
printf("Date format 3 is %s\n\n",date_str);
date(date_str,4);
time(time_str,0);
printf("Time of day format 0 = %s\n\n",time_str);
time(time_str,1);
printf("Time of day format 1 = %s\n\n",time_str);
time(time_str,2);
printf("Time of day format 2 = %s\n\n",time_str);
time(time_str,3);
date(date_str,1);
time(time_str,0);
printf("Printed at %s Hours on %s for Dr.Dobbs Journal.\n\n",
time_str,date_str);
}
/* date(srt,format) will fill a string with date formatted as follows:
format = 0 "May 11, 1981"
format = 1 "Monday, May 11, 1981"
format = 2 "11/5/1981"
format = 3 "Monday, 11/5/1981"
*/
date(str,format)
char *str; /* pointer to date string */
int format; /* format identifier */
{
char wname[10]; /* string for week day proper name */
char mname[12]; /* string for month proper name */
int year[1]; /* year, range 1978 to ????? */
int month[1]; /* month of the year, range 1 to 12 */
int mday[1]; /* day of the current month, range 0 to 31 */
int wday[1]; /* day of the week, range 0 to 6 */
if (get_date(year,month,mday,wday)){
printf("No clock board present in system\07\n");
return(-1);
}
name_month(mname,month);
name_week(wname,wday);
switch(format){
case 0:
sprintf(str,"%s %d, %d",mname,*mday,*year);
return(0);
case 1:
sprintf(str,"%s, %s %d, %d",wname,mname,*mday,*year);
return(0);
case 2:
sprintf(str,"%d/%d/%d",*mday,*month,*year);
return(0);
case 3:
sprintf(str,"%s, %d/%d/%d",wname,*mday,*month,*year);
return(0);
default:
printf("Date format argument ERROR !\07\n\n");
return(-1);
}
}
/* get_date(year,month,mday,wday) provides the basic data for formatting
a date string, fetched from the clock board and converted to a useable
set of values */
int get_date(year,month,mday,wday)
int *year; /* pointer to current year */
int *month; /* pointer to current month */
int *mday; /* pointer to day of the month */
int *wday; /* pointer to day of the week */
{
int tdays;
int port; /* input port number */
int pos; /* digit decimal position */
int tyear;
tdays = 0;
if (inp(CLOCK) == 0XFF ) /* no clock board present */
return(-1);
for (port = DAY1, pos = 1; port <= DAY10K; port++, pos *= 10){
tdays += (inp(port) & MASK) * pos;
}
*wday = tdays%7;
for (*year = BASE_YEAR; (tyear = tdays - ndays(year)) > 0;(*year)++){
tdays = tyear;
}
month_day(year,tdays,month,mday);
return (0);
}
/* month_day(year,yday,month,mday) is straight out of Kernighan and Ritchie
page 104, except that BDS C doesn't support intialisers so the special
BDS C "intw" kludge is used to initialise the day_tab array. Also the
leap year calaculation has been split off into a separate function as
it is generally useful.
*/
int month_day(year,yday,month,mday)
int *year; /* pointer to current year */
int yday; /* day of the year, range 1 to 366 */
int *month; /* pointer to month of the year */
int *mday; /* pointer to day of the month */
{
int i;
int lyear;
int day_tab[2][13];
initw(day_tab[0],"0,31,28,31,30,31,30,31,31,30,31,30,31");
initw(day_tab[1],"0,31,29,31,30,31,30,31,31,30,31,30,31");
lyear = leap(*year);
for (i = 1; yday > day_tab[lyear][i]; i++){
yday -= day_tab[lyear][i];
}
*month = i;
*mday = yday;
}
/* ndays(year) returns the number of days in the current year.
*/
int ndays(year)
int *year; /* pointer to current year */
{
return(leap(*year) ? 366 : 365);
}
/* leap(year) returns a flag to indicate if current year is a leap year.
*/
int leap(year)
int year; /* current year */
{
return (year%4 == 0 && year%100 != 0 || year%400 == 0);
}
/* name_month(mname,month) fills a string with the name of the the
current month.
*/
int name_month(mname,month)
char *mname; /* pointer to month name string */
int *month; /* pointer to current month */
{
switch(*month){
case 1:
strcpy(mname,"January");
return(0);
case 2:
strcpy(mname,"February");
return(0);
case 3:
strcpy(mname,"March");
return(0);
case 4:
strcpy(mname,"April");
return(0);
case 5:
strcpy(mname,"May");
return(0);
case 6:
strcpy(mname,"June");
return(0);
case 7:
strcpy(mname,"July");
return(0);
case 8:
strcpy(mname,"August");
return(0);
case 9:
strcpy(mname,"September");
return(0);
case 10:
strcpy(mname,"October");
return(0);
case 11:
strcpy(mname,"November");
return(0);
case 12:
strcpy(mname,"December");
return(0);
default:
printf("Month name ERROR !\n");
return(-1);
}
}
/* name_week(wname,wday) fills a string with the name of the current
week day.
*/
int name_week(wname,wday)
char *wname; /* pointer to week name string */
int *wday; /* pointer to current week day */
{
switch(*wday){
case 1:
strcpy(wname,"Sunday");
return(0);
case 2:
strcpy(wname,"Monday");
return(0);
case 3:
strcpy(wname,"Tuesday");
return(0);
case 4:
strcpy(wname,"Wednesday");
return(0);
case 5:
strcpy(wname,"Thursday");
return(0);
case 6:
strcpy(wname,"Friday");
return(0);
case 0:
strcpy(wname,"Saturday");
return(0);
default:
printf("Weekday name ERROR !\n");
return(-1);
}
}
/* time(str,format) fills a string with the time of day in the
following formats :
format 0 1800:15
format 1 18:00:15
format 2 18:00
*/
time(str,format)
char *str; /* string to fill with time */
int format; /* flag for format of string */
{
int t[6];
if (read_clock(t)){
printf("No clock board present in system !\07\n");
return(-1);
}
switch(format){
case 0:
sprintf(str,"%d%d%d%d:%d%d",t[0],t[1],t[2],t[3],t[4],t[5]);
return(0);
case 1:
sprintf(str,"%d%d:%d%d:%d%d",t[0],t[1],t[2],t[3],t[4],t[5]);
return(0);
case 2:
sprintf(str,"%d%d:%d%d",t[0],t[1],t[2],t[3]);
return(0);
default:
printf("Time of day format argument ERROR !\07\n\n");
return(-1);
}
}
/* read_clock(t) fills an array with the time of day digits read from
the clock board
*/
int read_clock(t)
int *t; /* array to store clock digits */
{
int port; /* clock port to read */
int ptr; /* pointer into digit array */
if (inp(CLOCK) == 0XFF ) /* no clock board present */
return(-1);
for (port = HOUR10, ptr = 0; port >= SEC1; port--, ptr++)
t[ptr] = inp(port) & MASK;
return(0);
}