中国DOS联盟

@echo off
setlocal enabledelayedexpansion


set infile=a.txt
:: set infile=%1


for %%i in (%infile%) do set outfile=%%~ni.b64


echo --->%outfile%
echo Content-Type: application/octet-stream; name="%infile%">>%outfile%
echo Content-Transfer-Encoding: base64>>%outfile%
echo Content-Disposition: inline; filename="%infile%">>%outfile%
echo.>>%outfile%


set t=ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/


for %%i in (%infile%) do set n=%%~zi
if [%n%]==[0] goto :eof
set /p=<nul>_.a
set /p=<nul>_.b
set /p=a<nul>_.a1
set /p=b<nul>_.b1
set m=1
set /a i=-2


:loop
set /a k="%m%&%n%"
if not [%k%]==[0] copy /b _.a + _.a1>nul
if not [%k%]==[0] copy /b _.b + _.b1>nul
set /a k="%i%&%n%"
if [%k%]==[0] goto :exit


type _.a1>>_.a1
type _.b1>>_.b1
set /a m=m*2
set /a i=i*2
goto :loop
:exit


fc /b %infile% _.a|find ":">_.a1
fc /b %infile% _.b|find ":">>_.a1
sort _.a1>_.b1
set n=
set m=0
set k=0
set q=0
for /f "tokens=1,2" %%i in (_.b1) do (
   if not [!n!]==[%%i] (
        set i=%%j
        call :dig !i:~0,1!
        set /a m=!m!*16+!j!
        call :dig !i:~1,1!
        set /a m=m*16+j
        set /a k=k+1
        if !k!==3 (
           set /a p="m>>18"
           call set x=!x!%%t:~!p!,1%%
           set /a p="(m>>12)&63"
           call set x=!x!%%t:~!p!,1%%
           set /a p="(m>>6)&63"
           call set x=!x!%%t:~!p!,1%%
           set /a p="m&63"
           call set x=!x!%%t:~!p!,1%%
           set /a q=q+1
           if [!q!]==[18] (
                           echo !x!>>%outfile%
                           set x=
                           set q=0)
           set m=0
           set k=0))
   set n=%%i)


if [%k%]==[1] (
           set /a p="m>>2"
           call set x=!x!%%t:~!p!,1%%
           set /a p="(m<<4)&63"
           call set x=!x!%%t:~!p!,1%%==)


if [%k%]==[2] (
           set /a p="m>>10"
           call set x=!x!%%t:~!p!,1%%
           set /a p="(m>>4)&63"
           call set x=!x!%%t:~!p!,1%%
           set /a p="(m<<2)&63"
           call set x=!x!%%t:~!p!,1%%=)


if not [%q%]==[0] echo %x%>>%outfile%


echo.>>%outfile%
echo ----->>%outfile%


del _.a
del _.a1
del _.b
del _.b1


goto :eof


:dig
set j=%1
if [%1]==[A] set j=10
if [%1]==[B] set j=11
if [%1]==[C] set j=12
if [%1]==[D] set j=13
if [%1]==[E] set j=14
if [%1]==[F] set j=15