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Convert the date/time functions to work with milliseconds since the

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julian epoch internally (instead of days since the epoch) in order to avoid
problems with floating-point roundoff error.  The interface is unchanged. (CVS 5215)

FossilOrigin-Name: ed35f8a98323dadb64b423615287fb24ea262ffb
This commit is contained in:
drh
2008-06-12 16:35:38 +00:00
parent 5e982b1c38
commit 85f477a141
4 changed files with 94 additions and 75 deletions
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109
src/date.c
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@@ -16,7 +16,7 @@
** sqlite3RegisterDateTimeFunctions() found at the bottom of the file.
** All other code has file scope.
**
** $Id: date.c,v 1.82 2008/06/12 13:50:00 drh Exp $
** $Id: date.c,v 1.83 2008/06/12 16:35:38 drh Exp $
**
** SQLite processes all times and dates as Julian Day numbers. The
** dates and times are stored as the number of days since noon
@@ -75,15 +75,15 @@
*/
typedef struct DateTime DateTime;
struct DateTime {
double rJD; /* The julian day number */
int Y, M, D; /* Year, month, and day */
int h, m; /* Hour and minutes */
int tz; /* Timezone offset in minutes */
double s; /* Seconds */
char validYMD; /* True if Y,M,D are valid */
char validHMS; /* True if h,m,s are valid */
char validJD; /* True if rJD is valid */
char validTZ; /* True if tz is valid */
sqlite3_int64 iJD; /* The julian day number times 86400000 */
int Y, M, D; /* Year, month, and day */
int h, m; /* Hour and minutes */
int tz; /* Timezone offset in minutes */
double s; /* Seconds */
char validYMD; /* True if Y,M,D are valid */
char validHMS; /* True if h,m,s are valid */
char validJD; /* True if iJD is valid */
char validTZ; /* True if tz is valid */
};
@@ -256,12 +256,12 @@ static void computeJD(DateTime *p){
B = 2 - A + (A/4);
X1 = 365.25*(Y+4716);
X2 = 30.6001*(M+1);
p->rJD = X1 + X2 + D + B - 1524.5;
p->iJD = (X1 + X2 + D + B - 1524.5)*86400000;
p->validJD = 1;
if( p->validHMS ){
p->rJD += (p->h*3600.0 + p->m*60.0 + p->s)/86400.0;
p->iJD += p->h*3600000 + p->m*60000 + p->s*1000;
if( p->validTZ ){
p->rJD -= p->tz*60/86400.0;
p->iJD -= p->tz*60000;
p->validYMD = 0;
p->validHMS = 0;
p->validTZ = 0;
@@ -320,7 +320,7 @@ static void setDateTimeToCurrent(sqlite3_context *context, DateTime *p){
double r;
sqlite3 *db = sqlite3_context_db_handle(context);
sqlite3OsCurrentTime(db->pVfs, &r);
p->rJD = r;
p->iJD = (sqlite3_int64)(r*86400000.0 + 0.5);
p->validJD = 1;
}
@@ -345,7 +345,6 @@ static int parseDateOrTime(
const char *zDate,
DateTime *p
){
memset(p, 0, sizeof(*p));
if( parseYyyyMmDd(zDate,p)==0 ){
return 0;
}else if( parseHhMmSs(zDate, p)==0 ){
@@ -354,7 +353,9 @@ static int parseDateOrTime(
setDateTimeToCurrent(context, p);
return 0;
}else if( sqlite3IsNumber(zDate, 0, SQLITE_UTF8) ){
getValue(zDate, &p->rJD);
double r;
getValue(zDate, &r);
p->iJD = (sqlite3_int64)(r*86400000.0 + 0.5);
p->validJD = 1;
return 0;
}
@@ -372,7 +373,7 @@ static void computeYMD(DateTime *p){
p->M = 1;
p->D = 1;
}else{
Z = p->rJD + 0.5;
Z = (p->iJD + 43200000)/86400000;
A = (Z - 1867216.25)/36524.25;
A = Z + 1 + A - (A/4);
B = A + 1524;
@@ -391,12 +392,11 @@ static void computeYMD(DateTime *p){
** Compute the Hour, Minute, and Seconds from the julian day number.
*/
static void computeHMS(DateTime *p){
int Z, s;
int s;
if( p->validHMS ) return;
computeJD(p);
Z = p->rJD + 0.5;
s = (p->rJD + 0.5 - Z)*86400000.0 + 0.5;
p->s = 0.001*s;
s = (p->iJD + 43200000) % 86400000;
p->s = s/1000.0;
s = p->s;
p->s -= s;
p->h = s/3600;
@@ -425,10 +425,11 @@ static void clearYMD_HMS_TZ(DateTime *p){
#ifndef SQLITE_OMIT_LOCALTIME
/*
** Compute the difference (in days) between localtime and UTC (a.k.a. GMT)
** Compute the difference (in milliseconds)
** between localtime and UTC (a.k.a. GMT)
** for the time value p where p is in UTC.
*/
static double localtimeOffset(DateTime *p){
static int localtimeOffset(DateTime *p){
DateTime x, y;
time_t t;
x = *p;
@@ -447,7 +448,7 @@ static double localtimeOffset(DateTime *p){
x.tz = 0;
x.validJD = 0;
computeJD(&x);
t = (x.rJD-2440587.5)*86400.0 + 0.5;
t = x.iJD/1000 - 2440587.5*86400.0;
#ifdef HAVE_LOCALTIME_R
{
struct tm sLocal;
@@ -489,7 +490,7 @@ static double localtimeOffset(DateTime *p){
y.validJD = 0;
y.validTZ = 0;
computeJD(&y);
return y.rJD - x.rJD;
return y.iJD - x.iJD;
}
#endif /* SQLITE_OMIT_LOCALTIME */
@@ -534,7 +535,7 @@ static int parseModifier(const char *zMod, DateTime *p){
*/
if( strcmp(z, "localtime")==0 ){
computeJD(p);
p->rJD += localtimeOffset(p);
p->iJD += localtimeOffset(p);
clearYMD_HMS_TZ(p);
rc = 0;
}
@@ -545,20 +546,20 @@ static int parseModifier(const char *zMod, DateTime *p){
/*
** unixepoch
**
** Treat the current value of p->rJD as the number of
** Treat the current value of p->iJD as the number of
** seconds since 1970. Convert to a real julian day number.
*/
if( strcmp(z, "unixepoch")==0 && p->validJD ){
p->rJD = p->rJD/86400.0 + 2440587.5;
p->iJD = p->iJD/86400.0 + 2440587.5*86400000.0;
clearYMD_HMS_TZ(p);
rc = 0;
}else if( strcmp(z, "utc")==0 ){
double c1;
computeJD(p);
c1 = localtimeOffset(p);
p->rJD -= c1;
p->iJD -= c1;
clearYMD_HMS_TZ(p);
p->rJD += c1 - localtimeOffset(p);
p->iJD += c1 - localtimeOffset(p);
rc = 0;
}
break;
@@ -573,15 +574,14 @@ static int parseModifier(const char *zMod, DateTime *p){
*/
if( strncmp(z, "weekday ", 8)==0 && getValue(&z[8],&r)>0
&& (n=r)==r && n>=0 && r<7 ){
int Z;
sqlite3_int64 Z;
computeYMD_HMS(p);
p->validTZ = 0;
p->validJD = 0;
computeJD(p);
Z = p->rJD + 1.5;
Z %= 7;
Z = ((p->iJD + 129600000)/86400000) % 7;
if( Z>n ) Z -= 7;
p->rJD += n - Z;
p->iJD += (n - Z)*86400000;
clearYMD_HMS_TZ(p);
rc = 0;
}
@@ -637,18 +637,18 @@ static int parseModifier(const char *zMod, DateTime *p){
*/
const char *z2 = z;
DateTime tx;
int day;
sqlite3_int64 day;
if( !isdigit(*(u8*)z2) ) z2++;
memset(&tx, 0, sizeof(tx));
if( parseHhMmSs(z2, &tx) ) break;
computeJD(&tx);
tx.rJD -= 0.5;
day = (int)tx.rJD;
tx.rJD -= day;
if( z[0]=='-' ) tx.rJD = -tx.rJD;
tx.iJD -= 43200000;
day = tx.iJD/86400000;
tx.iJD -= day*86400000;
if( z[0]=='-' ) tx.iJD = -tx.iJD;
computeJD(p);
clearYMD_HMS_TZ(p);
p->rJD += tx.rJD;
p->iJD += tx.iJD;
rc = 0;
break;
}
@@ -660,13 +660,13 @@ static int parseModifier(const char *zMod, DateTime *p){
computeJD(p);
rc = 0;
if( n==3 && strcmp(z,"day")==0 ){
p->rJD += r;
p->iJD += r*86400000.0 + 0.5;
}else if( n==4 && strcmp(z,"hour")==0 ){
p->rJD += r/24.0;
p->iJD += r*(86400000.0/24.0) + 0.5;
}else if( n==6 && strcmp(z,"minute")==0 ){
p->rJD += r/(24.0*60.0);
p->iJD += r*(86400000.0/(24.0*60.0)) + 0.5;
}else if( n==6 && strcmp(z,"second")==0 ){
p->rJD += r/(24.0*60.0*60.0);
p->iJD += r*(86400000.0/(24.0*60.0*60.0)) + 0.5;
}else if( n==5 && strcmp(z,"month")==0 ){
int x, y;
computeYMD_HMS(p);
@@ -678,7 +678,7 @@ static int parseModifier(const char *zMod, DateTime *p){
computeJD(p);
y = r;
if( y!=r ){
p->rJD += (r - y)*30.0;
p->iJD += (r - y)*30.0*86400000.0 + 0.5;
}
}else if( n==4 && strcmp(z,"year")==0 ){
computeYMD_HMS(p);
@@ -715,12 +715,13 @@ static int isDate(
){
int i;
const unsigned char *z;
int eType;
memset(p, 0, sizeof(*p));
if( argc==0 ){
setDateTimeToCurrent(context, p);
}else if( sqlite3_value_type(argv[0])==SQLITE_FLOAT ){
memset(p, 0, sizeof(*p));
p->rJD = sqlite3_value_double(argv[0]);
}else if( (eType = sqlite3_value_type(argv[0]))==SQLITE_FLOAT
|| eType==SQLITE_INTEGER ){
p->iJD = sqlite3_value_double(argv[0])*86400000.0 + 0.5;
p->validJD = 1;
}else{
z = sqlite3_value_text(argv[0]);
@@ -755,7 +756,7 @@ static void juliandayFunc(
DateTime x;
if( isDate(context, argc, argv, &x)==0 ){
computeJD(&x);
sqlite3_result_double(context, x.rJD);
sqlite3_result_double(context, x.iJD/86400000.0);
}
}
@@ -918,10 +919,10 @@ static void strftimeFunc(
y.M = 1;
y.D = 1;
computeJD(&y);
nDay = x.rJD - y.rJD + 0.5;
nDay = (x.iJD - y.iJD)/86400000.0 + 0.5;
if( zFmt[i]=='W' ){
int wd; /* 0=Monday, 1=Tuesday, ... 6=Sunday */
wd = ((int)(x.rJD+0.5)) % 7;
wd = ((x.iJD+43200000)/86400000) % 7;
sqlite3_snprintf(3, &z[j],"%02d",(nDay+7-wd)/7);
j += 2;
}else{
@@ -931,7 +932,7 @@ static void strftimeFunc(
break;
}
case 'J': {
sqlite3_snprintf(20, &z[j],"%.16g",x.rJD);
sqlite3_snprintf(20, &z[j],"%.16g",x.iJD/86400000.0);
j+=strlen(&z[j]);
break;
}
@@ -939,12 +940,12 @@ static void strftimeFunc(
case 'M': sqlite3_snprintf(3, &z[j],"%02d",x.m); j+=2; break;
case 's': {
sqlite3_snprintf(30,&z[j],"%d",
(int)((x.rJD-2440587.5)*86400.0 + 0.5));
(int)(x.iJD/1000.0 - 210866760000.0));
j += strlen(&z[j]);
break;
}
case 'S': sqlite3_snprintf(3,&z[j],"%02d",(int)x.s); j+=2; break;
case 'w': z[j++] = (((int)(x.rJD+1.5)) % 7) + '0'; break;
case 'w': z[j++] = (((x.iJD+129600000)/86400000) % 7) + '0'; break;
case 'Y': sqlite3_snprintf(5,&z[j],"%04d",x.Y); j+=strlen(&z[j]);break;
default: z[j++] = '%'; break;
}