SPEC:
Read 1376 byte binary file into uint16_t array
overwrite item[16] with dec<7360> = 0X1cc0
overwrite item[22] with dec<4912> = 0X1330
Write file to disk


sub prefix_hdr()  {
    $hsize=1376;  # Size of 16-bit grayscale tif header
    $hfn='d:/pic/misc/gray.3689x2462.hdr';  # Md5 ~29992
    $brfn='6s-254550.7360x4912.blue.raw';  # photoshops
    $rsize=-s $brfn;
    $mutant='blue.7360x4912.tif';
    open(H, "<$hfn");  binmode H;
    $bread=read(H, $hdr, $hsize);  close H;
    printf("Read $bread B from $hfn\n");
    @rgb=unpack("S*", $hdr); # RAW RGB UShort array
    printf("RGB[16]=%hu, [22]=%hu\n", $rgb[16], $rgb[22]);
    $rgb[16]=pack("S", 7360);  # Overwrite 3689 with 7360
    $rgb[22]=pack("S", 4912);  # 2462 -> 4912
    printf("FIXED?  RGB[16]=0X%04hu, [22]=%hu\n", $rgb[16], $rgb[22]);
}
Read 1376 B from d:/pic/misc/gray.1376b.3689x2462.hdr
RGB[16]=3689, [22]=2462     <<  PERFECT!
Argument "&#9492;^\" isn't numeric in printf  
Argument "0^S" isn't numeric in printf
FIXED?   RGB[16]=0X0000, [22]=0    <<<<<<WRONG
----------------------------------------------------
[download]

File reads fine. Unpacks perfectly and the numbers print

Pack is not packing the unsigned short:

pack(TEMPLATE,LIST) 
S    An unsigned short value.
Template="S"
List = one value, DECIMAL 7360
[download]

How does one do this in Perl

int xres=7360;
uint16_t my_ui16[688];
...
my_ui16[16] = (uint16_t)xres;
printf("Xres=%hu\n");
>> Xres=7360
[download]

============================================================

>> open my($outfh),'>:raw', 'stuff';

Opening the file, put it in BINMODE and reading into a blob worked.

Unpacking the binary blob into an intelligible unsigned int array also works.

But, writing does NOT work in BINmode? Reading didn't need ':raw<~!%_'

>> print $outfh pack 'S<*', @rgb; We skipped the part about overwriting the default values.

How is it possible to take a proven correct UINT16 array

read in Perl and overwrite 2 values? Generating a real, uint16 from scratch was the

obstacle. The PACK and UNPACK do not appear to do inverse operations.

Applying PACK() as documented with an 'S' produced unprintable junk.

The original array values printed perfectly as %uh, unsigned shorts.

How does one translate this C into perl?: </p

my_uint_16_var = (uint16_t) 7360;
[download]

It has to be a drop in replacement for the default value, the >>3689<< stock value, not ["&#9492;^\"] << ??

:RAW???

Those layers will also be ignored if you specifying a colon with no na
+me following it. In that case the default layer for the operating sys
+tem (:raw on Unix, :crlf on Windows) is used.
[download]

Binmode does away with any cr/lf funkiness.

regardless of platform, use binmode() on binary data, like images, for
+ example.
[download]

I am on Windoz, not *nix. Do I need :CRLF??? This is an OBSCURE Caveat!

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