int cyclic(unsigned char **sec) {
int grid_template, nx, ny, res, scan, flag_3_3, no_dx, basic_ang, sub_ang;
unsigned int npnts;
unsigned char *gds;
double dlon, units, lon1, lon2;
get_nxny(sec, &nx, &ny, &npnts, &res, &scan);
if (GDS_Scan_staggered(scan)) return 0;
if (nx <= 1 || ny <= 0) return 0;
grid_template = code_table_3_1(sec);
gds = sec[3];
flag_3_3 = flag_table_3_3(sec);
no_dx = 0;
if (flag_3_3 != -1) {
if ((flag_3_3 & 0x20) == 0) no_dx = 1;
}
if (no_dx) return 0;
if (grid_template == 0) {
basic_ang = GDS_LatLon_basic_ang(gds);
sub_ang = GDS_LatLon_sub_ang(gds);
units = basic_ang == 0 ? 0.000001 : (double) basic_ang / (double) sub_ang;
/* dlon has to be defined */
dlon = units * GDS_LatLon_dlon(gds);
return (fabs(nx*dlon-360.0) < ERROR);
}
if (grid_template == 10) {
if (output_order != wesn) return 0; // only works with we:sn order
lon1 = GDS_Mercator_lon1(gds);
lon2 = GDS_Mercator_lon2(gds);
if (lon2 < lon1) lon2 += 360.0;
dlon = (lon2-lon1)*nx/(nx-1.0);
return (fabs(dlon-360.0) < ERROR);
}
if (grid_template == 40) {
basic_ang = GDS_Gaussian_basic_ang(gds);
sub_ang = GDS_Gaussian_sub_ang(gds);
units = basic_ang == 0 ? 0.000001 : (double) basic_ang / (double) sub_ang;
/* dlon has to be defined */
dlon = units * GDS_Gaussian_dlon(gds);
return (fabs(nx*dlon-360.0) < ERROR);
}
return 0;
}
int rot_regular2ll(unsigned char **sec, double **lat, double **lon) {
unsigned char *gds;
double units, *tlon, *tlat;
double sp_lat, sp_lon, angle_rot;
double sin_a, cos_a;
int basic_ang, sub_ang, i;
int npnts;
double a, b, r, pr, gr, pm, gm, glat, glon;
/* get the lat-lon coordinates in rotated frame of referencee */
i = regular2ll(sec, lat, lon);
if (i != 0) return i;
gds = sec[3];
npnts = GB2_Sec3_npts(sec);
basic_ang = GDS_LatLon_basic_ang(gds);
sub_ang = GDS_LatLon_sub_ang(gds);
if (basic_ang != 0) {
units = (double) basic_ang / (double) sub_ang;
}
else {
units = 0.000001;
}
sp_lat = GDS_RotLatLon_sp_lat(gds) * units;
sp_lon = GDS_RotLatLon_sp_lon(gds) * units;
angle_rot = GDS_RotLatLon_rotation(gds) * units;
a = (M_PI/180.0) * (90.0+sp_lat);
b = (M_PI/180.0) * sp_lon;
r = (M_PI/180.0) * angle_rot;
sin_a = sin(a);
cos_a = cos(a);
tlat = *lat;
tlon = *lon;
for (i = 0; i < npnts; i++) {
pr = (M_PI/180.0) * *tlat;
gr = -(M_PI/180.0) * *tlon;
pm = asin(cos(pr)*cos(gr));
gm = atan2(cos(pr)*sin(gr),-sin(pr));
glat = (180.0/M_PI)*(asin(sin_a*sin(pm)-cos_a*cos(pm)*cos(gm-r)));
glon = -(180.0/M_PI)*(-b+atan2(cos(pm)*sin(gm-r),sin_a*cos(pm)*cos(gm-r)+cos_a*sin(pm)) );
*tlat++ = glat;
*tlon++ = glon;
}
return 0;
}
int cyclic(unsigned char **sec) {
int grid_template, nx, ny, res, scan, flag_3_3, no_dx, basic_ang, sub_ang;
unsigned int npnts;
unsigned char *gds;
double dlon, units;
get_nxny(sec, &nx, &ny, &npnts, &res, &scan);
if ((unsigned) (nx * ny) != npnts) return 0;
if (nx <= 0 || ny <= 0) return 0;
grid_template = code_table_3_1(sec);
gds = sec[3];
flag_3_3 = flag_table_3_3(sec);
no_dx = 0;
if (flag_3_3 != -1) {
if ((flag_3_3 & 0x20) == 0) no_dx = 1;
}
if (grid_template == 0) {
basic_ang = GDS_LatLon_basic_ang(gds);
sub_ang = GDS_LatLon_sub_ang(gds);
units = basic_ang == 0 ? 0.000001 : (double) basic_ang / (double) sub_ang;
dlon = units * GDS_LatLon_dlon(gds);
if (no_dx) dlon = 0.0;
dlon = nx * dlon;
return (fabs(dlon-360.0) < ERROR);
}
if (grid_template == 10) {
dlon = GDS_Mercator_dx(gds);
if (no_dx) dlon = 0.0;
dlon = nx * dlon;
return (fabs(dlon-360.0) < ERROR);
}
// need to add gaussian grid - a bit more complicated
return 0;
}
int small_grib(unsigned char **sec, int mode, float *data, double *lon, double *lat, unsigned int ndata,
int ix0, int ix1, int iy0, int iy1, FILE *out) {
int can_subset, grid_template;
int nx, ny, res, scan, new_nx, new_ny, i, j;
unsigned int sec3_len, new_ndata, k, npnts;
unsigned char *sec3, *new_sec[9];
double units;
int basic_ang, sub_ang, cyclic_grid;
float *new_data;
get_nxny(sec, &nx, &ny, &npnts, &res, &scan); /* get nx, ny, and scan mode of grid */
grid_template = code_table_3_1(sec);
// make a copy of the gds (sec3)
sec3_len = GB2_Sec3_size(sec);
sec3 = (unsigned char *) malloc(sec3_len);
for (k = 0; k < sec3_len; k++) sec3[k] = sec[3][k];
// make a copy of the sec[] with new sec3
new_sec[0] = sec[0];
new_sec[1] = sec[1];
new_sec[2] = sec[2];
new_sec[3] = sec3;
new_sec[4] = sec[4];
new_sec[5] = sec[5];
new_sec[6] = sec[6];
new_sec[7] = sec[7];
// new_sec[8] = sec[8]; not needed by writing routines
can_subset = 1;
if (lat == NULL || lon == NULL) can_subset = 0;
new_nx = ix1-ix0+1;
new_ny = iy1-iy0+1;
if (new_nx <= 0) fatal_error("small_grib, new_nx is <= 0","");
if (new_ny <= 0) fatal_error("small_grib, new_ny is <= 0","");
new_ndata = new_nx * new_ny;
cyclic_grid = 0;
if (can_subset) {
cyclic_grid = cyclic(sec);
// lat-lon grid - no thinning
if ((grid_template == 0 && sec3_len == 72) || (grid_template == 1 && sec3_len == 04)) {
uint_char(new_nx,sec3+30); // nx
uint_char(new_ny,sec3+34); // ny
basic_ang = GDS_LatLon_basic_ang(sec3);
sub_ang = GDS_LatLon_sub_ang(sec3);
if (basic_ang != 0) {
units = (double) basic_ang / (double) sub_ang;
}
else {
units = 0.000001;
}
i = lat[ idx(ix0,iy0,nx,ny,cyclic_grid) ] / units; // lat1
int_char(i,sec3+46);
i = lon[ idx(ix0,iy0,nx,ny,cyclic_grid) ] / units; // lon1
int_char(i,sec3+50);
i = lat[ idx(ix1,iy1,nx,ny,cyclic_grid) ] / units; // lat2
int_char(i,sec3+55);
i = lon[ idx(ix1,iy1,nx,ny,cyclic_grid) ] / units; // lon2
int_char(i,sec3+59);
}
else if ((grid_template == 40 && sec3_len == 72)) { // full Gaussian grid
uint_char(new_nx,sec3+30); // nx
uint_char(new_ny,sec3+34); // ny
basic_ang = GDS_Gaussian_basic_ang(sec3);
sub_ang = GDS_Gaussian_sub_ang(sec3);
if (basic_ang != 0) {
units = (double) basic_ang / (double) sub_ang;
}
else {
units = 0.000001;
}
i = lat[ idx(ix0,iy0,nx,ny,cyclic_grid) ] / units; // lat1
int_char(i,sec3+46);
i = lon[ idx(ix0,iy0,nx,ny,cyclic_grid) ] / units; // lon1
int_char(i,sec3+50);
i = lat[ idx(ix1,iy1,nx,ny,cyclic_grid) ] / units; // lat2
int_char(i,sec3+55);
i = lon[ idx(ix1,iy1,nx,ny,cyclic_grid) ] / units; // lon2
int_char(i,sec3+59);
}
// polar-stereo graphic, lambert conformal , no thinning
else if ((grid_template == 20 && sec3_len == 65) || // polar stereographic
(grid_template == 30 && sec3_len == 81)) { // lambert conformal
uint_char(new_nx,sec3+30); // nx
uint_char(new_ny,sec3+34); // ny
i = (int) (lat[ idx(ix0,iy0,nx,ny,cyclic_grid) ] * 1000000.0); // lat1
int_char(i,sec3+38);
i = (int) (lon[ idx(ix0,iy0,nx,ny,cyclic_grid) ] * 1000000.0); // lon1
int_char(i,sec3+42);
}
// mercator, no thinning
else if (grid_template == 10 && sec3_len == 72) { // mercator
uint_char(new_nx,sec3+30); // nx
uint_char(new_ny,sec3+34); // ny
units = 0.000001;
i = lat[ idx(ix0,iy0,nx,ny,cyclic_grid) ] / units; // lat1
int_char(i,sec3+38);
i = lon[ idx(ix0,iy0,nx,ny,cyclic_grid) ] / units; // lon1
int_char(i,sec3+42);
i = lat[ idx(ix1,iy1,nx,ny,cyclic_grid) ] / units; // lat2
int_char(i,sec3+51);
i = lon[ idx(ix1,iy1,nx,ny,cyclic_grid) ] / units; // lon2
int_char(i,sec3+55);
}
else {
can_subset = 0;
}
}
// copy data to a new array
if (can_subset) {
uint_char(new_ndata, sec3+6);
new_data = (float *) malloc(new_ndata * sizeof(float));
#pragma omp parallel for private(i,j,k)
for(j = iy0; j <= iy1; j++) {
k = (j-iy0)*(ix1-ix0+1);
for(i = ix0; i <= ix1; i++) {
new_data[(i-ix0) + k ] = data[ idx(i,j,nx,ny,cyclic_grid) ];
}
}
}
else {
new_ndata = ndata;
new_data = (float *) malloc(new_ndata * sizeof(float));
for (k = 0; k < ndata; k++) new_data[k] = data[k];
new_nx = nx;
new_ny = ny;
}
set_order(new_sec, output_order);
grib_wrt(new_sec, new_data, new_ndata, new_nx, new_ny, use_scale, dec_scale,
bin_scale, wanted_bits, max_bits, grib_type, out);
if (flush_mode) fflush(out);
free(new_data);
free(sec3);
return 0;
}
int regular2ll(unsigned char **sec, double **lat, double **lon) {
int basic_ang, sub_ang;
double units, dlat, dlon, lat1, lat2, lon1, lon2;
double e, w, n, s, dx, dy;
int i, j;
double *llat, *llon;
unsigned char *gds;
int nnx, nny, nres, nscan;
unsigned int nnpnts;
get_nxny(sec, &nnx, &nny, &nnpnts, &nres, &nscan);
gds = sec[3];
if (nny == -1) {
fprintf(stderr,"Sorry code does not handle variable ny yet\n");
return 0;
}
if ((*lat = (double *) malloc(nnpnts * sizeof(double))) == NULL) {
fatal_error("regular2ll memory allocation failed","");
}
if ((*lon = (double *) malloc(nnpnts * sizeof(double))) == NULL) {
fatal_error("regular2ll memory allocation failed","");
}
/* now figure out the grid coordinates mucho silly grib specification */
basic_ang = GDS_LatLon_basic_ang(gds);
sub_ang = GDS_LatLon_sub_ang(gds);
if (basic_ang != 0) {
units = (double) basic_ang / (double) sub_ang;
}
else {
units = 0.000001;
}
dlat = GDS_LatLon_dlat(gds) * units;
dlon = GDS_LatLon_dlon(gds) * units;
lat1 = GDS_LatLon_lat1(gds) * units;
lat2 = GDS_LatLon_lat2(gds) * units;
lon1 = GDS_LatLon_lon1(gds) * units;
lon2 = GDS_LatLon_lon2(gds) * units;
if (lon1 < 0.0 || lon2 < 0.0) fatal_error("BAD grid definition lon < zero","");
if (lon1 > 360.0 || lon2 > 360.0) fatal_error("BAD grid definition lon >= 360","");
if (lat1 < -90.0 || lat2 < -90.0 || lat1 > 90.0 || lat2 > 90.0) fatal_error("BAD grid definition lat","");
/* find S latitude and dy */
if (GDS_Scan_y(nscan)) {
s = lat1;
n = lat2;
}
else {
s = lat2;
n = lat1;
}
if (s > n) fatal_error("lat-lon grid: lat1 and lat2 inconsistent with scan order","");
if (nny != 1) {
dy = (n - s) / (nny - 1);
if (nres & 16) { /* lat increment is valid */
if (fabs(dy - dlat) > 0.001) fatal_error("lat-lon grid: dlat is inconsistent","");
}
}
else {
dy = 0.0;
}
// fprintf(stderr,">>> geo: dy %lf dlat %lf nres %d has dy %d has dx %d\n", dy, dlat, nres, nres & 16, nres & 32);
/* find W latitude and dx */
if ( GDS_Scan_row_rev(nscan) && (nny % 2 == 0) && ((nres & 32) == 0) ) {
fatal_error("grib GDS ambiguity","");
}
if (GDS_Scan_x(nscan)) {
w = lon1;
e = lon2;
if (GDS_Scan_row_rev(nscan) && ((nres & 32) == 0)) {
e = lon1 + (nnx-1) * dlon;
}
} else {
w = lon2;
e = lon1;
if (GDS_Scan_row_rev(nscan) && ((nres & 32) == 0)) {
w = lon1 - (nnx-1) * dlon;
}
}
if (e <= w) e += 360.0;
if (e-w > 360.0) e -= 360.0;
if (w < 0) {
w += 360.0;
e += 360.0;
}
/* lat-lon should be in a WE:SN order */
if (nnx > 0 && nny > 0) { /* non-thinned, potentially staggered grid */
/* put x[] and y[] values in lon[] and lat[] */
llat = *lat;
llon = *lon;
if (stagger(sec, nnpnts,llon,llat)) fatal_error("geo: stagger problem","");
if (nnx != 1) {
dx = (e-w) / (nnx - 1);
dx = fabs(dx);
if (nres & 32) { /* lon increment is valid */
if (fabs(dx - fabs(dlon)) > 0.001) fatal_error("lat-lon grid: dlon is inconsistent","");
}
}
else {
dx = 0.0;
}
dy = fabs(dy);
#pragma omp parallel for private(j)
for (j = 0; j < nnpnts; j++) {
llon[j] = lon1 + llon[j]*dx;
llon[j] = llon[j] >= 360.0 ? llon[j] - 360.0 : llon[j];
llon[j] = llon[j] < 0.0 ? llon[j] + 360.0 : llon[j];
llat[j] = lat1 + llat[j]*dy;
}
return 0;
}
/* must be thinned grid */
llat = *lat;
/* quasi-regular grid */
for (j = 0; j < nny; j++) {
for (i = 0; i < variable_dim[j]; i++) {
*llat++ = s + j*dy;
}
}
llon = *lon;
/* quasi-regular grid */
for (j = 0; j < nny; j++) {
dx = (e-w) / (variable_dim[j]-1);
for (i = 0; i < variable_dim[j]; i++) {
*llon++ = w + i*dx >= 360.0 ? w + i*dx - 360.0: w + i*dx;
}
}
return 0;
} /* end regular2ll() */
