50 lines
1.3 KiB
C
50 lines
1.3 KiB
C
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/* include file containing all AODT library global variables */
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#include "../inc/odtlib.h"
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int aodtv64_readtopo( char *,float,float,int * );
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int aodtv64_readtopo( char *topofile, float mlat, float mlon, int *ichar)
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/* Determine land/water flag for data point using low resolution
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topograpy file TOPOLRES.
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Inputs : mlat - latitude of data point in question
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mlon - longitude of data point in question
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Outputs : ichar - <0=error,1=land,2=water
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Return : -31 : error accessing topography file
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-32 : error reading topography file
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71 : cyclone is over land
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0 : cyclone is over water
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*/
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{
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FILE *fdi;
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int error,iret;
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short buf;
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long llat, llon, position,bytes=768;
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/*---------------------------------------------------------------------------*/
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*ichar=-99;
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llat=(long)mlat;
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llon=(long)mlon;
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fdi = fopen(topofile, "rb") ;
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if (fdi == NULL) {
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/* failed to open topography file */
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return -31;
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}
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llat=89-llat;
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llon=-1*(llon+1);
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if(llon<0) llon=llon+360;
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position=(llat*bytes)+((2*llon)+48);
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error=fseek (fdi,position ,SEEK_SET ) ;
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if(error!=0) {
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/* error reading topography file */
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return -32;
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}
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fread(&buf,sizeof(buf),1,fdi);
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*ichar=(buf==0)?2:1;
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fclose(fdi);
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iret=0;
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if(*ichar==1) iret=71;
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return iret;
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}
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