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#include <stdint.h>
static void copy_bits(uint8_t *out, unsigned int out_pos, const uint8_t *in, unsigned int in_pos, unsigned int length)
{
unsigned int offset, chunk_size;
uint8_t temp, mask;
// skip untouched out bytes
offset = out_pos / 8;
out += offset;
out_pos -= offset * 8;
// skip untouched in bytes
offset = in_pos / 8;
in += offset;
in_pos -= offset * 8;
while(length > 0)
{
chunk_size = (in_pos < out_pos) ? 8 - out_pos : 8 - in_pos;
if(chunk_size == 0) chunk_size = 8;
if(chunk_size > length) chunk_size = length;
temp = ((*in) << in_pos);
temp >>= out_pos;
mask = 0xff << (8 - chunk_size);
mask = /*0xff ^*/ (mask >> out_pos);
*out |= mask & temp;
in_pos += chunk_size;
if(in_pos >= 8)
{
in++;
in_pos -= 8;
}
out_pos += chunk_size;
if(out_pos >= 8)
{
out++;
out_pos -= 8;
}
length -= chunk_size;
}
}
static void reverse_data(uint8_t *a, int len)
{
int i;
uint8_t temp;
for(i = len / 2 - 1; i >= 0; i--)
{
temp = a[i];
a[i] = a[len-1-i];
a[len-1-i] = temp;
}
}
static uint64_t reverse_bits(uint64_t a, int bits)
{
int i;
uint64_t b = 0;
for(i = 0; i < bits; i++)
{
b = (b << 1) | (a & 1);
a >>= 1;
}
return b;
}
static int64_t sign_extend(uint64_t a, int bits)
{
int64_t sret;;
if((a & (1ULL << (bits - 1))) != 0)
{
a = ((uint64_t)0xffffffffffffffffLL << bits) | a;
memcpy(&sret, &a, 8);
return sret;
}
return a;
}
#define B_SKIP 0
#define B_STR 1
#define B_INT 2
#define B_LSB 4
#define B_LE 8
#define B_SIGN 16
#define BSKIP B_SKIP
#define BSTR B_STR
#define BMSB B_INT
#define BLSB (B_INT|B_LSB)
#define BLE (B_INT|B_LE)
#define BSMSB (B_INT|B_SIGN)
#define BSLSB (B_INT|B_LSB|B_SIGN)
#define BSLE (B_INT|B_LE|B_SIGN)
#if BYTE_ORDER == LITTLE_ENDIAN
#define BMO BLE
#define BSMO BSLE
#else
#define BMO BMSB
#define BSMO BSMSB
#endif
static int lcrypt_bget(lua_State *L)
{
int count = 0, argc = lua_gettop(L);
size_t length;
const unsigned char *in = (const unsigned char*)luaL_checklstring(L, 1, &length);
int i, type, bits, offset = luaL_checkint(L, 2);
length *= 8;
for(i = 3; i <= argc && offset < (int)length; i += 2)
{
type = luaL_checkint(L, i);
if(i+1 > argc)
bits = length;
else
bits = luaL_checkint(L, i+1);
if(offset + bits > (int)length) bits = length - offset;
if(type == B_SKIP)
{
count--;
}
else if(type == B_STR)
{
int len = (bits + 7) / 8;
uint8_t * data = (uint8_t *)alloca(len);
memset(data, 0, len);
copy_bits(data, 0, in, offset, bits);
lua_pushlstring(L, (char*)data, len);
}
else // integer
{
uint64_t ret = 0;
copy_bits((uint8_t*)&ret, sizeof(ret) * 8 - bits, in, offset, bits);
#if BYTE_ORDER == LITTLE_ENDIAN
reverse_data((uint8_t*)&ret, sizeof(ret));
#endif
if((type & B_LSB) == B_LSB) ret = reverse_bits(ret, bits);
#if BYTE_ORDER == LITTLE_ENDIAN
if((type & B_LE) == B_LE) reverse_data((uint8_t*)&ret, (bits+7)/8);
#else
if((type & B_LE) == B_LE) reverse_data((uint8_t*)&ret + 8-(bits+7)/8, (bits+7)/8);
#endif
if((type & B_SIGN) == B_SIGN)
lua_pushnumber(L, sign_extend(ret, bits));
else
lua_pushnumber(L, ret);
}
count++;
offset += bits;
}
return count;
}
static int lcrypt_bput(lua_State *L)
{
int argc = lua_gettop(L);
int i, type, bits = 0, offset = 0, len = 0;
size_t length;
for(i = 1; i <= argc; i += 3)
{
type = luaL_checkint(L, i+1);
if(type == B_STR && lua_isnil(L, i+2) == 1)
{
(void)luaL_checklstring(L, i, &length);
bits = (lua_isnil(L, i+2) == 1) ? length * 8 : luaL_checkint(L, i+2);
if(bits > (int)length * 8) bits = length * 8;
}
else
{
bits = luaL_checkint(L, i+2);
}
len += bits;
}
len = (len + 7) / 8;
uint8_t * ret = (uint8_t *)alloca(len);
memset(ret, 0, len);
for(i = 1; i <= argc; i += 3)
{
type = luaL_checkint(L, i+1);
if(type == B_STR)
{
const uint8_t *in = (const uint8_t *)luaL_checklstring(L, i, &length);
bits = (lua_isnil(L, i+2) == 1) ? length * 8 : luaL_checkint(L, i+2);
if(bits > (int)length * 8) bits = length * 8;
copy_bits(ret, offset, in, 0, bits);
}
else if(type != B_SKIP) // integer
{
uint64_t in;
bits = luaL_checkint(L, i+2);
if((type & B_SIGN) == B_SIGN)
{
int64_t sin = luaL_checknumber(L, i);
memcpy(&in, &sin, 8);
}
else
{
in = luaL_checknumber(L, i);
}
#if BYTE_ORDER == LITTLE_ENDIAN
reverse_data((uint8_t*)&in, sizeof(in));
#endif
if((type & B_LSB) == B_LSB)
{
in = reverse_bits(in, 64);
copy_bits(ret, offset, (uint8_t*)&in, 0, bits);
}
else if((type & B_LE) == B_LE)
{
reverse_data((uint8_t*)&in, sizeof(in));
copy_bits(ret, offset, (uint8_t*)&in, 0, bits);
}
else
copy_bits(ret, offset, (uint8_t*)&in, sizeof(in) * 8 - bits, bits);
}
offset += bits;
}
lua_pushlstring(L, (char*)ret, len);
return 1;
}
static void lcrypt_start_bits(lua_State *L)
{
ADD_FUNCTION(L, bget); ADD_FUNCTION(L, bput);
ADD_CONSTANT(L, BSKIP); ADD_CONSTANT(L, BSTR); ADD_CONSTANT(L, BMSB); ADD_CONSTANT(L, BLSB);
ADD_CONSTANT(L, BLE); ADD_CONSTANT(L, BSMSB); ADD_CONSTANT(L, BSLSB); ADD_CONSTANT(L, BSLE);
ADD_CONSTANT(L, BMO); ADD_CONSTANT(L, BSMO);
}
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