'\" t
.\"     srecord - The "srecord" program.
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.ds n) srec_binary
.TH srec_binary 5 SRecord "Reference Manual"
.SH NAME
srec_binary \- binary file format
.XX "srec_binary(5)" "binary file format"
.SH DESCRIPTION
It is possible to read and write binary files using \f[I]srec_cat\fP(1).
.SS File Holes
A file hole is a portion of a regular file that contains null characters
and is not stored in any data block on disk.  Holes are a long-standing
feature of Unix files.  For instance, the following Unix command creates
a file in which the first bytes are a hole:
.RS
.nf
.ft CW
$ echo -n "X" | dd of=/tmp/hole bs=1024 seek=6
.ft P
.fi
.RE
Now \f[CW]/tmp/hole\fP has 6,145 characters (6,144 null characters
plus an X character), yet the file occupies just one data block on
disk.
.PP
File holes were introduced to avoid wasting disk space.  They are
used extensively by database applications and, more generally, by all
applications that perform hashing on files.
.PP
See
http://www.oreilly.com/catalog/linuxkernel2/chapter/ch17.pdf
for more information.
.SS Reading
The size of binary files is taken from the size of the file on the file system.
If the file has "holes" these will read as blocks of zero data,
as there is no elegant way to detect Unix file holes.
In general, you probably want to use the \fB\-unfill\fP filter
to find and remove large swathes of zero bytes.
.SS Writing
In producing a binary file, \f[I]srec_cat\fP(1) honours the address
information and places the data into the binary file at the addresses
specified in the hex file.  This usually results on "holes" in the file.
Sometimes alarmingly large file sizes are reported as a result.
.PP
If you are on a brain-dead operating system without file "holes" then
there are going to be real data blocks containing real zero bytes,
and consuming real amounts of disk space.  Upgrade \- I suggest Linux.
.PP
To make a file of the size you expect, use
.RS
srec_info foo.s19
.RE
to find the lowest address, then use
.RS
srec_cat foo.s19 --intel -offset -\f[I]n\fP -o foo.bin -binary
.RE
where \f[I]n\fP is the lowest address present in the \f[CW]foo.s19\fP
file, as reported by \f[I]srec_info\fP(1).  The \f[B]negative\fP offset
serves to move the data down to have an origin of zero.
.so ../man1/z_copyright.so
.\" vim:ts=8:sw=4:et