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Endianess tweaks.

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This commit is contained in:
curt 2001-01-03 18:06:34 +00:00
parent 43f544d7df
commit 78368f7c38
3 changed files with 27 additions and 7 deletions
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3
src/Prep/DemRaw2ascii/README Normal file
View file

@ -0,0 +1,3 @@
This tool preprocesses RAW binary dems such as you would find here:
http://www.ngdc.noaa.gov/seg/topo/globe.shtml

28
src/Prep/DemRaw2ascii/rawdem.c
View file

@ -72,6 +72,9 @@ void rawReadDemHdr( fgRAWDEM *raw, char *hdr_file ) {
exit(-1);
}
/* default to big endian if nothing else */
raw->big_endian = 1;
/* process each line */
while ( (fgets(line, 256, hdr) != NULL) ) {
/* printf("%s", line); */
@ -99,7 +102,13 @@ void rawReadDemHdr( fgRAWDEM *raw, char *hdr_file ) {
value[i-offset] = '\0';
/* printf("key='%s' value='%s'\n", key, value); */
if ( strcmp(key, "NROWS") == 0 ) {
if ( strcmp(key, "BYTEORDER") == 0 ) {
if ( strcmp( value, "M" ) == 0 ) {
raw->big_endian = 1;
} else {
raw->big_endian = 0;
}
} else if ( strcmp(key, "NROWS") == 0 ) {
raw->nrows = atoi(value);
} else if ( strcmp(key, "NCOLS") == 0 ) {
raw->ncols = atoi(value);
@ -208,11 +217,18 @@ void rawReadNextRow( fgRAWDEM *raw, int index ) {
for ( i = 0; i < raw->ncols; i++ ) {
/* printf("hi = %d lo = %d\n", buf[2*i], buf[2*i + 1]); */
#if defined( BIG_ENDIAN )
value = ( (buf[2*i]) << 8 ) | buf[2*i + 1];
#else
value = ( (buf[2*i + 1]) << 8 ) | buf[2*i];
#endif
/* the endianness of the data is determined by the creator of
the data file, we see it as a byte stream. The actual
endianess is in the header file someplace but I don't yet
know how to read it out. So for the time being we assume
that the data is always big endian */
if ( raw->big_endian ) {
value = ( (buf[2*i]) << 8 ) | buf[2*i + 1];
} else {
value = ( (buf[2*i + 1]) << 8 ) | buf[2*i];
}
raw->strip[index][i] = value;
if ( value < raw->min ) { raw->min = value; }

3
src/Prep/DemRaw2ascii/rawdem.h
View file

@ -32,6 +32,7 @@
typedef struct {
/* header info */
int big_endian; /* true if big, false if little */
int nrows; /* number of rows */
int ncols; /* number of cols */
int ulxmap; /* X coord of center of upper left pixel in arcsec */
@ -42,7 +43,7 @@ typedef struct {
int ydim; /* Y dimension of a pixel */
int tmp_min; /* current 1x1 degree tile minimum */
int tmp_max; /* current 1x1 degree tile maximum */
/* file ptr */
int fd; /* Raw DEM file descriptor */