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Merge pull request #17 from sgk/cache-vars

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Cache working variables for speed
This commit is contained in:
OSQZSS 2015-07-20 08:41:51 +09:00
commit b182ac048e
1 changed files with 22 additions and 20 deletions
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gpssim.c
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@ -177,6 +177,12 @@ typedef struct
double af1;
double af2;
double tgd;
// Working variables follow
double n; // Mean motion (Average angular velocity)
double sq1e2; // sqrt(1-e^2)
double A; // A
double omgkdot; // (OmegaDot-OmegaEdot)
} ephem_t;
typedef struct
@ -392,9 +398,7 @@ void satpos(ephem_t eph, gpstime_t g, double *pos, double *vel, double *clk)
// http://www.ngs.noaa.gov/gps-toolbox/bc_velo.htm
double tk;
double a;
double mk;
double mkdot;
double ek;
double ekold;
double ekdot;
@ -406,7 +410,6 @@ void satpos(ephem_t eph, gpstime_t g, double *pos, double *vel, double *clk)
double ukdot;
double cuk,suk;
double ok;
double okdot;
double sok,cok;
double ik;
double ikdot;
@ -416,7 +419,7 @@ void satpos(ephem_t eph, gpstime_t g, double *pos, double *vel, double *clk)
double xpk,ypk;
double xpkdot,ypkdot;
double relativistic, OneMinusecosE, sqrtOneMinuse2, tmp;
double relativistic, OneMinusecosE, tmp;
tk = g.sec - eph.toe.sec;
@ -425,11 +428,7 @@ void satpos(ephem_t eph, gpstime_t g, double *pos, double *vel, double *clk)
else if(tk<-SECONDS_IN_HALF_WEEK)
tk += SECONDS_IN_WEEK;
a = eph.sqrta*eph.sqrta;
mkdot = sqrt(GM_EARTH/(a*a*a)) + eph.deltan;
mk = eph.m0 + mkdot*tk;
mk = eph.m0 + eph.n*tk;
ek = mk;
ekold = ek + 1.0;
@ -443,14 +442,12 @@ void satpos(ephem_t eph, gpstime_t g, double *pos, double *vel, double *clk)
sek = sin(ek);
cek = cos(ek);
ekdot = mkdot/OneMinusecosE;
ekdot = eph.n/OneMinusecosE;
relativistic = -4.442807633E-10*eph.ecc*eph.sqrta*sek;
sqrtOneMinuse2 = sqrt(1.0 - eph.ecc*eph.ecc);
pk = atan2(sqrtOneMinuse2*sek,cek-eph.ecc) + eph.aop;
pkdot = sqrtOneMinuse2*ekdot/OneMinusecosE;
pk = atan2(eph.sq1e2*sek,cek-eph.ecc) + eph.aop;
pkdot = eph.sq1e2*ekdot/OneMinusecosE;
s2pk = sin(2.0*pk);
c2pk = cos(2.0*pk);
@ -460,8 +457,8 @@ void satpos(ephem_t eph, gpstime_t g, double *pos, double *vel, double *clk)
cuk = cos(uk);
ukdot = pkdot*(1.0 + 2.0*(eph.cus*c2pk - eph.cuc*s2pk));
rk = a*OneMinusecosE + eph.crc*c2pk + eph.crs*s2pk;
rkdot = a*eph.ecc*sek*ekdot + 2.0*pkdot*(eph.crs*c2pk - eph.crc*s2pk);
rk = eph.A*OneMinusecosE + eph.crc*c2pk + eph.crs*s2pk;
rkdot = eph.A*eph.ecc*sek*ekdot + 2.0*pkdot*(eph.crs*c2pk - eph.crc*s2pk);
ik = eph.inc0 + eph.idot*tk + eph.cic*c2pk + eph.cis*s2pk;
sik = sin(ik);
@ -473,8 +470,7 @@ void satpos(ephem_t eph, gpstime_t g, double *pos, double *vel, double *clk)
xpkdot = rkdot*cuk - ypk*ukdot;
ypkdot = rkdot*suk + xpk*ukdot;
okdot = eph.omgdot - OMEGA_EARTH;
ok = eph.omg0 + tk*okdot - OMEGA_EARTH*eph.toe.sec;
ok = eph.omg0 + tk*eph.omgkdot - OMEGA_EARTH*eph.toe.sec;
sok = sin(ok);
cok = cos(ok);
@ -484,8 +480,8 @@ void satpos(ephem_t eph, gpstime_t g, double *pos, double *vel, double *clk)
tmp = ypkdot*cik - ypk*sik*ikdot;
vel[0] = -okdot*pos[1] + xpkdot*cok - tmp*sok;
vel[1] = okdot*pos[0] + xpkdot*sok + tmp*cok;
vel[0] = -eph.omgkdot*pos[1] + xpkdot*cok - tmp*sok;
vel[1] = eph.omgkdot*pos[0] + xpkdot*sok + tmp*cok;
vel[2] = ypk*cik*ikdot + ypkdot*sik;
clk[0] = eph.af0 + tk*(eph.af1 + tk*eph.af2) + relativistic - eph.tgd;
@ -946,6 +942,12 @@ int readRinexNav(ephem_t eph[], char *fname)
}
else
break;
// Update the working variables
eph[sv].A = eph[sv].sqrta * eph[sv].sqrta;
eph[sv].n = sqrt(GM_EARTH/(eph[sv].A*eph[sv].A*eph[sv].A)) + eph[sv].deltan;
eph[sv].sq1e2 = sqrt(1.0 - eph[sv].ecc*eph[sv].ecc);
eph[sv].omgkdot = eph[sv].omgdot - OMEGA_EARTH;
}
fclose(fp);