as: Symbol Value

1 
1 5.5.1 Value
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1 
1 The value of a symbol is (usually) 32 bits.  For a symbol which labels a
1 location in the text, data, bss or absolute sections the value is the
1 number of addresses from the start of that section to the label.
1 Naturally for text, data and bss sections the value of a symbol changes
1 as 'ld' changes section base addresses during linking.  Absolute
1 symbols' values do not change during linking: that is why they are
1 called absolute.
1 
1    The value of an undefined symbol is treated in a special way.  If it
1 is 0 then the symbol is not defined in this assembler source file, and
1 'ld' tries to determine its value from other files linked into the same
1 program.  You make this kind of symbol simply by mentioning a symbol
1 name without defining it.  A non-zero value represents a '.comm' common
1 declaration.  The value is how much common storage to reserve, in bytes
1 (addresses).  The symbol refers to the first address of the allocated
1 storage.
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