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/*
* lpack.c
* a Lua library for packing and unpacking binary data
* Luiz Henrique de Figueiredo <lhf@tecgraf.puc-rio.br>
* 29 Jun 2007 19:27:20
* This code is hereby placed in the public domain.
* with contributions from Ignacio Castaño <castanyo@yahoo.es> and
* Roberto Ierusalimschy <roberto@inf.puc-rio.br>.
*/
#define OP_ZSTRING 'z' /* zero-terminated string */
#define OP_BSTRING 'p' /* string preceded by length byte */
#define OP_WSTRING 'P' /* string preceded by length word */
#define OP_SSTRING 'a' /* string preceded by length size_t */
#define OP_STRING 'A' /* string */
#define OP_FLOAT 'f' /* float */
#define OP_DOUBLE 'd' /* double */
#define OP_NUMBER 'n' /* Lua number */
#define OP_CHAR 'c' /* char */
#define OP_BYTE 'b' /* byte = unsigned char */
#define OP_SHORT 'h' /* short */
#define OP_USHORT 'H' /* unsigned short */
#define OP_INT 'i' /* int */
#define OP_UINT 'I' /* unsigned int */
#define OP_LONG 'l' /* long */
#define OP_ULONG 'L' /* unsigned long */
#define OP_LITTLEENDIAN '<' /* little endian */
#define OP_BIGENDIAN '>' /* big endian */
#define OP_NATIVE '=' /* native endian */
#include <ctype.h>
#include <stdint.h>
#include <string.h>
#include "lua.h"
#include "lualib.h"
#include "lauxlib.h"
static void badcode(lua_State *L, int c)
{
char s[]="bad code `?'";
s[sizeof(s)-3]=c;
luaL_argerror(L,1,s);
}
static int doendian(int c)
{
int x=1;
int e=*(char*)&x;
if (c==OP_LITTLEENDIAN) return !e;
if (c==OP_BIGENDIAN) return e;
if (c==OP_NATIVE) return 0;
return 0;
}
static void doswap(int swap, void *p, size_t n)
{
if (swap)
{
char *a=p;
int i,j;
for (i=0, j=n-1, n=n/2; n--; i++, j--)
{
char t=a[i]; a[i]=a[j]; a[j]=t;
}
}
}
#define UNPACKNUMBER(OP,T) \
case OP: \
{ \
T a; \
int m=sizeof(a); \
if (i+m>len) goto done; \
memcpy(&a,s+i,m); \
i+=m; \
doswap(swap,&a,m); \
lua_pushinteger(L,(lua_Integer)a); \
++n; \
break; \
}
#define UNPACKSTRING(OP,T) \
case OP: \
{ \
T l; \
int m=sizeof(l); \
if (i+m>len) goto done; \
memcpy(&l,s+i,m); \
doswap(swap,&l,m); \
if (i+m+l>len) goto done; \
i+=m; \
lua_pushlstring(L,s+i,l); \
i+=l; \
++n; \
break; \
}
static int l_unpack(lua_State *L) /** unpack(s,f,[init]) */
{
size_t len;
const char *s=luaL_checklstring(L,1,&len);
const char *f=luaL_checkstring(L,2);
int i=luaL_optnumber(L,3,1)-1;
int n=0;
int swap=0;
lua_pushnil(L);
while (*f)
{
int c=*f++;
int N=1;
if (isdigit(*f))
{
N=0;
while (isdigit(*f)) N=10*N+(*f++)-'0';
if (N==0 && c==OP_STRING) { lua_pushliteral(L,""); ++n; }
}
while (N--) switch (c)
{
case OP_LITTLEENDIAN:
case OP_BIGENDIAN:
case OP_NATIVE:
{
swap=doendian(c);
N=0;
break;
}
case OP_STRING:
{
++N;
if (i+N>len) goto done;
lua_pushlstring(L,s+i,N);
i+=N;
++n;
N=0;
break;
}
case OP_ZSTRING:
{
size_t l;
if (i>=len) goto done;
l=strlen(s+i);
lua_pushlstring(L,s+i,l);
i+=l+1;
++n;
break;
}
UNPACKSTRING(OP_BSTRING, unsigned char)
UNPACKSTRING(OP_WSTRING, unsigned short)
UNPACKSTRING(OP_SSTRING, size_t)
UNPACKNUMBER(OP_NUMBER, lua_Number)
UNPACKNUMBER(OP_DOUBLE, double)
UNPACKNUMBER(OP_FLOAT, float)
UNPACKNUMBER(OP_CHAR, int8_t)
UNPACKNUMBER(OP_BYTE, uint8_t)
UNPACKNUMBER(OP_SHORT, int16_t)
UNPACKNUMBER(OP_USHORT, uint16_t)
UNPACKNUMBER(OP_INT, int32_t)
UNPACKNUMBER(OP_UINT, uint32_t)
UNPACKNUMBER(OP_LONG, int64_t)
UNPACKNUMBER(OP_ULONG, uint64_t)
case ' ': case ',':
break;
default:
badcode(L,c);
break;
}
}
done:
lua_pushnumber(L,i+1);
lua_replace(L,-n-2);
return n+1;
}
#define PACKNUMBER(OP,T) \
case OP: \
{ \
T a=(T)luaL_checknumber(L,i++); \
doswap(swap,&a,sizeof(a)); \
luaL_addlstring(&b,(void*)&a,sizeof(a)); \
break; \
}
#define PACKSTRING(OP,T) \
case OP: \
{ \
size_t l; \
const char *a=luaL_checklstring(L,i++,&l); \
T ll=(T)l; \
doswap(swap,&ll,sizeof(ll)); \
luaL_addlstring(&b,(void*)&ll,sizeof(ll)); \
luaL_addlstring(&b,a,l); \
break; \
}
static int l_pack(lua_State *L) /** pack(f,...) */
{
int i=2;
const char *f=luaL_checkstring(L,1);
int swap=0;
luaL_Buffer b;
luaL_buffinit(L,&b);
while (*f)
{
int c=*f++;
int N=1;
if (isdigit(*f))
{
N=0;
while (isdigit(*f)) N=10*N+(*f++)-'0';
}
while (N--) switch (c)
{
case OP_LITTLEENDIAN:
case OP_BIGENDIAN:
case OP_NATIVE:
{
swap=doendian(c);
N=0;
break;
}
case OP_STRING:
case OP_ZSTRING:
{
size_t l;
const char *a=luaL_checklstring(L,i++,&l);
luaL_addlstring(&b,a,l+(c==OP_ZSTRING));
break;
}
PACKSTRING(OP_BSTRING, unsigned char)
PACKSTRING(OP_WSTRING, unsigned short)
PACKSTRING(OP_SSTRING, size_t)
PACKNUMBER(OP_NUMBER, lua_Number)
PACKNUMBER(OP_DOUBLE, double)
PACKNUMBER(OP_FLOAT, float)
PACKNUMBER(OP_CHAR, int8_t)
PACKNUMBER(OP_BYTE, uint8_t)
PACKNUMBER(OP_SHORT, int16_t)
PACKNUMBER(OP_USHORT, uint16_t)
PACKNUMBER(OP_INT, int32_t)
PACKNUMBER(OP_UINT, uint32_t)
PACKNUMBER(OP_LONG, int64_t)
PACKNUMBER(OP_ULONG, uint64_t)
case ' ': case ',':
break;
default:
badcode(L,c);
break;
}
}
luaL_pushresult(&b);
return 1;
}
static const luaL_reg R[] =
{
{"pack", l_pack},
{"unpack", l_unpack},
{NULL, NULL}
};
int luaopen_lpack(lua_State *L)
{
#ifdef USE_GLOBALS
lua_register(L,"bpack",l_pack);
lua_register(L,"bunpack",l_unpack);
#else
luaI_openlib(L, LUA_STRLIBNAME, R, 0);
#endif
return 0;
}
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