1984-07-12 15:18:13 +00:00
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.\" $Header$
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1984-07-12 14:14:54 +00:00
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.TH A.OUT 5
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.SH NAME
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a.out \- universal assembler load format
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.SH DESCRIPTION
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The load files produced by the universal assemblers look very
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much alike.
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These load files consist of sequences of variable length
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records, each describing a part of the initialized memory.
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Bss type memory is left uninitialized by the universal assembler
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and has to be initialized at run-time.
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The EM header em_head will perform this task on most systems.
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Each record consists of a \fIcount\fP, an \fIaddress\fP and
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\fIcount\fP bytes.
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The first byte should be placed at \fIaddress\fP, the second at
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\fIaddress+1\fP, etc.
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.nf
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struct loadf {
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unsigned short l_addr[2] ; /* address */
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short l_cnt ; /* count */
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unsigned char data[] ; /* data */
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} ;
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.fi
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This representation is machine dependent in two ways.
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First, the byte order in the first three fields is the byte order
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of the machine the universal assembler is running.
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Second, the format of the address differs from machine to machine.
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.br
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For example, for the Intel 8086 the first entry contains a
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16-bit offset and the second entry a segment number.
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The segment number has to be multiplied by 16 and added to
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the addres to obtain the address of the first byte to be
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initialized.
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.br
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The PDP 11 version stores the address in l_addr[0] and the type
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of the initialized memory in l_addr[1].
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Types 1 and 3 are absolute, 4 is text, 5 is data and 6 BSS.
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.br
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For all other currently available machines the
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array of shorts is 'replaced' by a long.
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This long contains the 32-bit address.
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.SH "SEE ALSO"
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uni_ass(VI)
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.SH BUGS
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