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Improve the performance of getBits().

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Well, it's not used much, although it's much faster now, heh.
This commit is contained in:
Unknown W. Brackets 2013-11-16 19:10:21 -08:00
parent e77b8bc5b5
commit d446659b2a
1 changed files with 18 additions and 6 deletions
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24
Core/Font/PGF.cpp
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@ -34,14 +34,26 @@ static bool isJPCSPFont(const char *fontName) {
}
// Gets a number of bits from an offset.
// TODO: Make more efficient.
static int getBits(int numBits, const u8 *buf, size_t pos) {
int v = 0;
for (int i = 0; i < numBits; i++) {
v = v | (((buf[pos >> 3] >> (pos & 7)) & 1) << i);
pos++;
_dbg_assert_msg_(SCEFONT, numBits <= 32, "Unable to return more than 32 bits, %d requested", numBits);
const size_t wordpos = pos >> 5;
const u32 *wordbuf = (const u32 *)buf;
const u8 bitoff = pos & 31;
// Might just be in one, has to be within two.
if (bitoff + numBits < 32) {
const u32 mask = (1 << numBits) - 1;
return (wordbuf[wordpos] >> bitoff) & mask;
} else {
int v = wordbuf[wordpos] >> bitoff;
const u8 done = 32 - bitoff;
const u8 remaining = numBits - done;
const u32 mask = (1 << remaining) - 1;
v |= (wordbuf[wordpos + 1] & mask) << done;
return v;
}
return v;
}
static std::vector<int> getTable(const u8 *buf, int bpe, size_t length) {