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#include "pack.h"
////////////////////////////////////////////////////////////////////////////////
//
// Pack
//
int Pack(ui8* buf, ui32 value) {
ui8* p = buf;
for (;;) {
ui8 v = (ui8)value & 0x7f;
value >>= 7;
if (!value) {
*p++ = v;
break;
}
*p++ = (v | 0x80);
}
return (int)(p - buf);
}
ui32 Unpack(const ui8*& data) {
ui32 value = 0;
const ui8* p = data;
for (int off = 0;; ++p, off += 7) {
value |= (*p & 0x7f) << off;
if ((*p & 0x80) == 0) {
++p;
break;
}
}
data = p;
return value;
}
////////////////////////////////////////////////////////////////////////////////
//
// PackU32
//
int PackU32(ui32 value, void* buf) {
ui8* p = (ui8*)buf; // 654 3210 <-- bit of 'value' (7 bits total)
if (value < (1u << 7)) { // [0--- ----]
p[0] = (ui8)value; // ^ ^
return 1; // MSB LSB
}
value -= (1u << 7); // DC BA98 7654 3210 <-- bit of 'value' (14 == 0xD bits total)
if (value < (1u << 14)) { // [10-- ----] [---- ----]
p[1] = (ui8)value; value >>= 8;
p[0] = 0x80 | (ui8)value;
return 2;
}
value -= (1u << 14); // And so on...
if (value < (1u << 21)) { // [110- ----] [---- ----] [---- ----]
p[2] = (ui8)value; value >>= 8;
p[1] = (ui8)value; value >>= 8;
p[0] = 0xc0 | (ui8)value;
return 3;
}
value -= (1u << 21);
if (value < (1u << 28)) { // [1110 ----] [---- ----] [---- ----] [---- ----]
p[3] = (ui8)value; value >>= 8;
p[2] = (ui8)value; value >>= 8;
p[1] = (ui8)value; value >>= 8;
p[0] = 0xe0 | (ui8)value;
return 4;
} // ...but for largest numbers, whole first byte is reserved.
value -= (1u << 28); // [1111 0000] [---- ----] [---- ----] [---- ----] [---- ----]
p[4] = (ui8)value; value >>= 8;
p[3] = (ui8)value; value >>= 8;
p[2] = (ui8)value; value >>= 8;
p[1] = (ui8)value;
p[0] = 0xf0;
return 5;
}
int UnpackU32(ui32* value, const void* buf) {
const ui8* p = (const ui8*)buf;
ui8 b = p[0];
if (!(b & 0x80)) {
*value = b;
return 1;
}
if (!(b & 0x40)) {
*value = 0x80 + (((b & 0x3f) << 8) | p[1]);
return 2;
}
if (!(b & 0x20)) {
*value = 0x4080 + (((b & 0x1f) << 16) | (p[1] << 8) | p[2]);
return 3;
}
if (!(b & 0x10)) {
*value = 0x204080 + (((b & 0x0f) << 24) | (p[1] << 16) | (p[2] << 8) | p[3]);
return 4;
}
*value = 0x10204080 + ((p[1] << 24) | (p[2] << 16) | (p[3] << 8) | p[4]);
return 5;
}
int SkipU32(const void* buf) {
static const i8 skip[16] = { 1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 4, 5 };
int i = ((const ui8*)buf)[0] >> 4;
return skip[i];
}
////////////////////////////////////////////////////////////////////////////////
//
// PackU64
//
int PackU64(ui64 value, void* buf) { // Packing scheme is analogous to PackU32()
ui8* p = (ui8*)buf;
if (value < (1u << 7)) {
p[0] = (ui8)value;
return 1;
}
value -= (1u << 7);
if (value < (1u << 14)) {
p[1] = (ui8)value; value >>= 8;
p[0] = 0x80 | (ui8)value;
return 2;
}
value -= (1u << 14);
if (value < (1u << 21)) {
p[2] = (ui8)value; value >>= 8;
p[1] = (ui8)value; value >>= 8;
p[0] = 0xc0 | (ui8)value;
return 3;
}
value -= (1u << 21);
if (value < (1u << 28)) {
p[3] = (ui8)value; value >>= 8;
p[2] = (ui8)value; value >>= 8;
p[1] = (ui8)value; value >>= 8;
p[0] = 0xe0 | (ui8)value;
return 4;
}
value -= (1u << 28);
if (value < (ui64(1) << 35)) {
p[4] = (ui8)value; value >>= 8;
p[3] = (ui8)value; value >>= 8;
p[2] = (ui8)value; value >>= 8;
p[1] = (ui8)value; value >>= 8;
p[0] = 0xf0 | (ui8)value;
return 5;
}
value -= ui64(1) << 35;
if (value < (ui64(1) << 42)) {
p[5] = (ui8)value; value >>= 8;
p[4] = (ui8)value; value >>= 8;
p[3] = (ui8)value; value >>= 8;
p[2] = (ui8)value; value >>= 8;
p[1] = (ui8)value; value >>= 8;
p[0] = 0xf8 | (ui8)value;
return 6;
}
value -= ui64(1) << 42;
if (value < (ui64(1) << 49)) { // [1111 110-] [---- ----] ... (+ 5 bytes)
p[6] = (ui8)value; value >>= 8;
p[5] = (ui8)value; value >>= 8;
p[4] = (ui8)value; value >>= 8;
p[3] = (ui8)value; value >>= 8;
p[2] = (ui8)value; value >>= 8;
p[1] = (ui8)value; value >>= 8;
p[0] = 0xfc | (ui8)value;
return 7;
}
value -= ui64(1) << 49;
if (value < (ui64(1) << 56)) { // [1111 1110] [---- ----] ... (+ 6 bytes)
p[7] = (ui8)value; value >>= 8;
p[6] = (ui8)value; value >>= 8;
p[5] = (ui8)value; value >>= 8;
p[4] = (ui8)value; value >>= 8;
p[3] = (ui8)value; value >>= 8;
p[2] = (ui8)value; value >>= 8;
p[1] = (ui8)value; value >>= 8;
p[0] = 0xfe | (ui8)value;
return 8;
}
value -= ui64(1) << 56; // [1111 1111] [---- ----] ... (+ 7 bytes)
p[8] = (ui8)value; value >>= 8; // ^
p[7] = (ui8)value; value >>= 8; // not a zero; contains actual bit
p[6] = (ui8)value; value >>= 8;
p[5] = (ui8)value; value >>= 8;
p[4] = (ui8)value; value >>= 8;
p[3] = (ui8)value; value >>= 8;
p[2] = (ui8)value; value >>= 8;
p[1] = (ui8)value; value >>= 8;
p[0] = 0xff;
return 9;
}
int UnpackU64(ui64* value, const void* buf) {
const ui8* p = (const ui8*)buf;
ui8 b = p[0];
if (!(b & 0x80)) {
*value = b;
return 1;
}
if (!(b & 0x40)) {
*value = 0x80 + (((b & 0x3f) << 8) | p[1]);
return 2;
}
if (!(b & 0x20)) {
*value = 0x4080 + (((b & 0x1f) << 16) | (p[1] << 8) | p[2]);
return 3;
}
if (!(b & 0x10)) {
*value = 0x204080 + (((b & 0x0f) << 24) | (p[1] << 16) | (p[2] << 8) | p[3]);
return 4;
}
if (!(b & 0x08)) {
*value = 0x10204080 + (
(ui64(b & 0x07) << 32) |
(ui32(p[1]) << 24) |
( p[2] << 16) |
( p[3] << 8) |
p[4]
);
return 5;
}
if (!(b & 0x04)) {
*value = 0x0810204080ull + (
(ui64(b & 0x03) << 40) |
(ui64(p[1]) << 32) |
(ui32(p[2]) << 24) |
( p[3] << 16) |
( p[4] << 8) |
p[5]
);
return 6;
}
if (!(b & 0x02)) {
*value = 0x040810204080ull + (
(ui64(b & 0x01) << 48) |
(ui64(p[1]) << 40) |
(ui64(p[2]) << 32) |
(ui32(p[3]) << 24) |
( p[4] << 16) |
( p[5] << 8) |
p[6]
);
return 7;
}
if (!(b & 0x01)) {
*value = 0x02040810204080ull + (
(ui64(p[1]) << 48) |
(ui64(p[2]) << 40) |
(ui64(p[3]) << 32) |
(ui32(p[4]) << 24) |
( p[5] << 16) |
( p[6] << 8) |
p[7]
);
return 8;
}
*value = 0x0102040810204080ull + (
(ui64(p[1]) << 56) |
(ui64(p[2]) << 48) |
(ui64(p[3]) << 40) |
(ui64(p[4]) << 32) |
(ui32(p[5]) << 24) |
( p[6] << 16) |
( p[7] << 8) |
p[8]
);
return 9;
}
#define REPEAT_16(x) x, x, x, x, x, x, x, x, x, x, x, x, x, x, x, x
#define REPEAT_32(x) REPEAT_16(x), REPEAT_16(x)
#define REPEAT_64(x) REPEAT_32(x), REPEAT_32(x)
#define REPEAT_128(x) REPEAT_64(x), REPEAT_64(x)
int SkipU64(const void* buf) {
static const i8 skip[256] = {
REPEAT_128(1), REPEAT_64(2), REPEAT_32(3), REPEAT_16(4),
5, 5, 5, 5, 5, 5, 5, 5, 6, 6, 6, 6, 7, 7, 8, 9
};
return skip[*(const ui8*)buf];
}
#undef REPEAT_16
#undef REPEAT_32
#undef REPEAT_64
#undef REPEAT_128
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