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@end example

@end table

@node Libtcc
@chapter The @code{libtcc} library

The @code{libtcc} library enables you to use TCC as a backend for
dynamic code generation. 

Read the @file{libtcc.h} to have an overview of the API. Read
@file{libtcc_test.c} to have a very simple example.

The idea consists in giving a C string containing the program you want
to compile directly to @code{libtcc}. Then you can access to any global
symbol (function or variable) defined.

@node devel
@chapter Developer's guide

This chapter gives some hints to understand how TCC works. You can skip
it if you do not intend to modify the TCC code.

@section File reading

The @code{BufferedFile} structure contains the context needed to read a
file, including the current line number. @code{tcc_open()} opens a new
file and @code{tcc_close()} closes it. @code{inp()} returns the next
character.

@section Lexer

@code{next()} reads the next token in the current
file. @code{next_nomacro()} reads the next token without macro
expansion.

@code{tok} contains the current token (see @code{TOK_xxx})
constants. Identifiers and keywords are also keywords. @code{tokc}
contains additional infos about the token (for example a constant value
if number or string token).

@section Parser

The parser is hardcoded (yacc is not necessary). It does only one pass,
except:

@itemize

@item For initialized arrays with unknown size, a first pass 
is done to count the number of elements.

@item For architectures where arguments are evaluated in 
reverse order, a first pass is done to reverse the argument order.

@end itemize

@section Types

The types are stored in a single 'int' variable. It was chosen in the
first stages of development when tcc was much simpler. Now, it may not
be the best solution.

@example
#define VT_INT        0  /* integer type */
#define VT_BYTE       1  /* signed byte type */
#define VT_SHORT      2  /* short type */
#define VT_VOID       3  /* void type */
#define VT_PTR        4  /* pointer */
#define VT_ENUM       5  /* enum definition */
#define VT_FUNC       6  /* function type */
#define VT_STRUCT     7  /* struct/union definition */
#define VT_FLOAT      8  /* IEEE float */
#define VT_DOUBLE     9  /* IEEE double */
#define VT_LDOUBLE   10  /* IEEE long double */
#define VT_BOOL      11  /* ISOC99 boolean type */
#define VT_LLONG     12  /* 64 bit integer */
#define VT_LONG      13  /* long integer (NEVER USED as type, only
                            during parsing) */
#define VT_BTYPE      0x000f /* mask for basic type */
#define VT_UNSIGNED   0x0010  /* unsigned type */
#define VT_ARRAY      0x0020  /* array type (also has VT_PTR) */
#define VT_VLA        0x20000 /* VLA type (also has VT_PTR and VT_ARRAY) */
#define VT_BITFIELD   0x0040  /* bitfield modifier */
#define VT_CONSTANT   0x0800  /* const modifier */
#define VT_VOLATILE   0x1000  /* volatile modifier */
#define VT_DEFSIGN    0x2000  /* signed type */

#define VT_STRUCT_SHIFT 18   /* structure/enum name shift (14 bits left) */
@end example

When a reference to another type is needed (for pointers, functions and
structures), the @code{32 - VT_STRUCT_SHIFT} high order bits are used to
store an identifier reference.

The @code{VT_UNSIGNED} flag can be set for chars, shorts, ints and long
longs.

Arrays are considered as pointers @code{VT_PTR} with the flag
@code{VT_ARRAY} set. Variable length arrays are considered as special
arrays and have flag @code{VT_VLA} set instead of @code{VT_ARRAY}.

The @code{VT_BITFIELD} flag can be set for chars, shorts, ints and long
longs. If it is set, then the bitfield position is stored from bits
VT_STRUCT_SHIFT to VT_STRUCT_SHIFT + 5 and the bit field size is stored
from bits VT_STRUCT_SHIFT + 6 to VT_STRUCT_SHIFT + 11.

@code{VT_LONG} is never used except during parsing.

During parsing, the storage of an object is also stored in the type
integer:

@example
#define VT_EXTERN  0x00000080  /* extern definition */
#define VT_STATIC  0x00000100  /* static variable */
#define VT_TYPEDEF 0x00000200  /* typedef definition */
#define VT_INLINE  0x00000400  /* inline definition */
#define VT_IMPORT  0x00004000  /* win32: extern data imported from dll */
#define VT_EXPORT  0x00008000  /* win32: data exported from dll */
#define VT_WEAK    0x00010000  /* win32: data exported from dll */
@end example