C语言学习趣事_MSCRT_IO_SourceFile

前些时候，贴了一段微软的printf代码，园子里的大侠们说要看看output的代码，这不最近有幸看了微软的

output代码，所以贴上来给园子里大侠看看。

Tip：

源代码版权归微软所有，这里仅贴出来供大家看看。

?/***
*output.c - printf style output to a FILE
*
*   Copyright (c) 1989-1991, Microsoft Corporation. All rights reserved.
*
*Purpose:
*   This file contains the code that does all the work for the
*   printf family of functions. It should not be called directly, only
*   by the *printf functions. We don't make any assumtions about the
*   sizes of ints, longs, shorts, or long doubles, but if types do overlap,
*   we also try to be efficient. We do assume that pointers are the same
*   size as either ints or longs.
*   If CPRFLAG is defined, defines _cprintf instead.
*   **** DOESN'T CURRENTLY DO MTHREAD LOCKING ****
*
*Revision History:
*   06-01-89 PHG   Module created
*   08-28-89 JCR   Added cast to get rid of warning (no object changes)
*   02-15-90 GJF   Fixed copyright
*   03-19-90 GJF   Made calling type _CALLTYPE1 and added #include
*           <cruntime.h>.
*   03-26-90 GJF   Changed LOCAL macro to incorporate _CALLTYPE4. Placed
*           prototype for _output() in internal.h and #include-d
*           it.
*   08-01-90 SBM   Compiles cleanly with -W3, moved _cfltcvt_tab and
*           typedefs DOUBLE and LONGDOUBLE to new header
*           <fltintrn.h>, formerly named <struct.h>
*   09-05-90 SBM   First attempt at adding CPRFLAG and code to generate
*           cprintf. Anything in #ifdef CPRFLAG untested.
*           Still needs to have locking added for MTHREAD case.
*   10-03-90 GJF   New-style function declarators.
*   01-02-91 SRW   Added _WIN32_ conditional for 'C' and 'S' format chars.
*   01-16-91 GJF   ANSI naming.
*   01-16-91 SRW   Added #include of maketabc.out (_WIN32_)
*   04-09-91 PNT   Use the _CRUISER_ mapping for _MAC_
*   04-16-91 SRW   Fixed #include of maketabc.out (_WIN32_)
*   04-25-91 SRW   Made nullstring static
*   05-20-91 GJF   Moved state table for Win32 inline (_WIN32_).
*   09-12-91 JCR   Bumped conversion buffer size to be ANSI-compliant
*   09-17-91 IHJ   Add partial UNICODE (%ws, %wc) support
*   09-28-91 GJF   Merged with crt32 and crtdll versions. For now, 9-17-91
*           change is built only for Win32, not Dosx32 (_WIN32_).
*   10-22-91 ETC   Complete wchar_t/mb support under _INTL. For now,
*           9-28-91 change is additionally under !_INTL. Bug fix:
*           ints and pointers are longs.
*   11-19-91 ETC   Added support for _wsprintf, _vwsprintf with WPRFLAG;
*           added %tc %ts (generic string handling).
*   12-05-91 GDP   Bug fix: va_arg was used inconsistently for double
*   12-19-91 ETC   Added some comments on wsprintf optimization, undones;
*           check return on malloc.
*   03-25-92 DJM   POSIX support
*   04-16-92 KRS   Support new ISO {s|f}wprintf with Unicode format string.
*   06-08-92 SRW   Modified to not use free and malloc for mbtowc conversion.
*   06-10-92 KRS   Fix glitch in previous change.
*   07-14-92 TVB   Added Alpha support (quad stuff).
*   07-17-92 KRS   Fix typo which broke WPRFLAG support.
*   04-16-93 SKS   Fix bug in 'S' option logic.
*   07-16-93 SRW   ALPHA Merge
*   08-17-93 CFW   Avoid mapping tchar macros incorrectly if _MBCS defined.
*
*******************************************************************************/

/* temporary hack to minimize changes. This should go into fltintrn.h */
#if defined(_M_MRX000) || defined(_M_ALPHA) || defined(_M_PPC)
#define DOUBLE double
#endif

#include <cruntime.h>
#include <limits.h>
#include <string.h>
#include <stddef.h>
#include <stdio.h>
#include <stdarg.h>
#include <cvt.h>
#include <conio.h>
#include <internal.h>
#include <fltintrn.h>
#include <stdlib.h>
#include <ctype.h>
#include <assert.h>

/* inline keyword is non-ANSI C7 extension */
/* CONSIDER: move to cruntime.h! */
#if !defined(_MSC_VER) || defined(__STDC__)
#define __inline static
#else
/* UNDONE: compiler is broken */
#define __inline static
#endif

#if defined(WPRFLAG) && !defined(_UNICODE)
#define _UNICODE 1
#endif
#ifdef _MBCS    /* always want either Unicode or SBCS for tchar.h */
#undef _MBCS
#endif
#include <tchar.h>

/* this macro defines a function which is private and as fast as possible: */
/* for example, in C 6.0, it might be static _fastcall <type> near. */
#define LOCAL(x) static x _CALLTYPE4

/* int/long/short/pointer sizes */

/* the following should be set depending on the sizes of various types */
#define LONG_IS_INT      1       /* 1 means long is same size as int */
#define SHORT_IS_INT         0       /* 1 means short is same size as int */
#define LONGDOUBLE_IS_DOUBLE 1       /* 1 means long double is same as double */
#define PTR_IS_INT       1       /* 1 means ptr is same size as int */
#define PTR_IS_LONG      1       /* 1 means ptr is same size as long */

#if LONG_IS_INT
    #define get_long_arg(x) (long)get_int_arg(x)
#endif

#ifndef WPRFLAG
#if SHORT_IS_INT
    #define get_short_arg(x) (short)get_int_arg(x)
#endif
#endif

#if PTR_IS_INT
    #define get_ptr_arg(x)

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