stfe.3

来自「<B>Digital的Unix操作系统VAX 4.2源码</B>」· 3 代码 · 共 235 行

.TH stfe 3 RISC
.SH Name
stfe, st_filebegin, st_endallfiles, st_fileend, st_blockbegin, st_textblock, st_blockend, st_procend, st_procbegin, st_str_idn, st_sym_idn, st_abs_ifd_index, st_fglobal_idn, st_psym_idn_offset, st_pdadd_idn \- routines that provide a high-level interface to basic functions needed
to access and add to the symbol table
.SH Syntax
.nf
.B #include <syms.h>
.PP
.ft B
long st_filebegin (filename)
char *filename;
.PP
.ft B
long st_endallfiles ()
.PP
.ft B
long st_fileend (idn)
long idn;
.PP
.ft B
long st_blockbegin(iss, value, sc)
long iss;
long value;
long sc;
.PP
.ft B
long st_textblock()
.PP
.ft B
long st_blockend(size)
long size;
.PP
.ft B
long st_procend(idn)
long idn
.PP
.ft B
long st_procbegin (idn)
long idn;
.PP
.ft B
char *st_str_idn (idn)
long idn;
.PP
.ft B
char *st_sym_idn (idn, value, sc, st, index)
long idn;
long *value;
long *sc;
long *st;
long *index;
.PP
.ft B
long st_abs_ifd_index (ifd, index)
long ifd;
long index;
.PP
.ft B
long st_fglobal_idn (idn)
long idn;
.PP
.ft B
pSYMR st_psym_idn_offset (idn, offset)
long idn;
long offset;
.PP
.ft B
long st_pdadd_idn (idn)
long idn;
.fi
.ft R
.br
.SH Description
The
.B stfe
routines provide a high-level interface to the symbol table based on common
needs of the compiler front-ends. 
.TP 20
.I st_filebegin
Takes a file name and calls 
.I st_fdadd (see 
.MS stfd 3 ).
If it is a new file, a symbol is added to the symbol table that for that
file or symbol, and the user supplied routine,
.I st_feinit,
is called. This allows special file parameters to be initialized.
For example, the C front-end adds basic type auxiliaries to each file's
aux table so that all variables of that type can refer to a single
instance instead of making individual copies of them. 
The routine
.I st_filebegin\fR
returns a dense number that references the symbol added for this file.
It tracks files as they appear in a CPP line directive with a stack.
It detects (from the order of the CPP directives) 
that a file ends and calls 
.I st_filend.
If a file is closed with a 
.I st_fileend, 
a new instance of the filename is created.  For example, multiply included 
files.
.TP 20
.I st_fileend
Requires 
the dense number from the corresponding 
.I st_filebegin call for the file
in question. It then generates an end symbol and patches the references so
that the index field of the begin file points to that of one beyond 
the end file. The end file points to the begin file.
.TP 20
.I st_endallfiles
Is called at the end of execution to close off all files that have not been
ended by previous calls to 
.I st_filebegin. 
CPP directives might not
reflect the return to the original source file; therefore, this routine can
possibly close many files.
.TP 20
.I st_blockbegin
Supports both language blocks (for example, 
C's left curly brace blocks), beginning of
structures, and unions. If the storage class is scText,
it is the former; if it is scInfo, it is one of the latter.
The iss (index into string space) specifies the name of the
structure/etc, if any. 
.PP
If the storage class is scText, we must check the result of 
.I st_blockbegin.
It returns a dense number for outer blocks and a zero for nested blocks.
The non-zero block number should be used in the BGNB ucode.
Users of languages without nested blocks that provide variable 
declarations can ignore the rest of this paragraph.
Nested blocks are two-staged: one stage occurs when 
the language block is detected and the other stage occurs when
the block has content. If the block has content (for example, local 
variables), the front-end must call 
.I st_textblock 
to get a non-zero dense number for the block's BGNB ucode. If the block 
does not have content and 
.I st_textblock
is not called, the block's 
.I st_blockbegin
and
.I st_blockend
do not produce block and end symbols.
.PP
If it is scInfo,
.I st_blockbegin 
creates a begin block symbol in the symbol table and returns a dense 
number referencing it.  The dense number is necessary to build the 
auxiliary required to reference the structure/etc. It goes in the aux 
after the TIR along with a file index. This dense number is also noted 
in a stack of blocks used by 
.I st_blockend.
.PP
The 
.I st_blockbegin should not be called for
language blocks when the front-end is not producing debugging
symbols.
.PP
The
.I st_blockend
requires that blocks occur in a nested fashion. It retrieves the
dense number for the most recently started block and creates a
corresponding end symbol. As in 
.I fileend, 
both the begin and end symbol index fields point at the other end's symbol.
If the symbol ends a structure/etc., as determined by the storage class of the
begin symbol, the size parameter is assigned to the begin symbol's value field.
It is usually the size of the structure or max value of a enum.
We only know it at this point. The dense number of the end symbol
is returned so that the ucode ENDB can use it.
If it is an ignored text block, the dense number is zero and no ENDB
should be generated.
.PP
In general, defined external procedures or functions appear in the
symbols table and the externals table. The external table definition must
occur first through the use of a 
.I st_extadd.  After that definition,
.I st_procbegin
can be called with a dense number referring to the external
symbol for that procedure. It checks to be sure we have a defined
procedure (by checking the storage class). It 
adds a procedure symbol to the symbol table. The external's index
should point at its auxiliary data type information (or if 
debugging is off, indexNil).
This index is copied into
the regular symbol's index field or a copy of its type is generated
(if the external is in a different file than the regular symbol).
Next, we put the index to symbol in the external's index field. The external's
dense number is used as a block number in ucodes referencing it and
is used to add a procedure when in the 
.I st_pdadd_idn.
.TP 20
.I st_procend
Creates an end symbol and fixes the indices as in 
.I blockend 
and
.I fileend,
except that the end procedure reference is kept in the begin procedure's
aux rather than in the index field (because the begin procedure has a type
as well as an end reference). This must be called with the dense
number of the procedure's external symbol as an argument and returns
the dense number of the end symbol to be used in the END ucode.
.TP 20
.I st_str_idn
Returns the string associated with symbol or external referenced by the
dense number argument. If the symbol was anonymous (for example, 
there is not a
symbol), a (char *), -1 is returned.
.TP 20
.I st_sym_idn
Returns the same result as 
.I st_str_idn, except that the rest of the fields of the symbol specified 
by the
.I idn
are returned in the arguments.
.TP 20
.I st_fglobal_idn
Returns a 1 if the symbol associated with the specified idn is non-static;
otherwise, a 0 is returned.
.TP 20
.I st_abs_ifd_index
Returns the absolute offset for a dense number. If the symbol is
global, the global's index is returned. If the symbol occurred in a
file, the sum of all symbols in files occurring before that file
and the symbol's index within the file is returned.
.TP 20
.I st_pdadd_idn
Adds an entry to the procedure table for the 
.I st_proc entry 
generated by procbegin. This should be called when the front-end generates code
for the procedure in question.
.SH See Also
stcu(3), stfd(3), sym.h(5), stsupport.h(5)