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Make util phexdigit array reusable

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class template base_uint had its own private lookup table.
This is saving 256 bytes per instantiation.

The result is not spectacular as bitcoin-qt has only shrinked of
about 1Kb but it is still valid improvement.

Also, I have replaced a for loop with a memset() call.

Made CBigNum::SetHex() use the new HexDigit() function.

Signed-off-by: Olivier Langlois <olivier@olivierlanglois.net>
This commit is contained in:
Olivier Langlois
2013-10-10 12:35:51 -04:00
parent 15b48ab036
commit f171ec0c7d
5 changed files with 34 additions and 14 deletions
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15
src/uint256.h
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@@ -14,7 +14,12 @@
typedef long long int64;
typedef unsigned long long uint64;
extern const signed char p_util_hexdigit[256]; // defined in util.cpp
inline signed char HexDigit(char c)
{
return p_util_hexdigit[(unsigned char)c];
}
inline int Testuint256AdHoc(std::vector<std::string> vArg);
@@ -305,8 +310,7 @@ public:
void SetHex(const char* psz)
{
for (int i = 0; i < WIDTH; i++)
pn[i] = 0;
memset(pn,0,sizeof(pn));
// skip leading spaces
while (isspace(*psz))
@@ -317,19 +321,18 @@ public:
psz += 2;
// hex string to uint
static const unsigned char phexdigit[256] = { 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,1,2,3,4,5,6,7,8,9,0,0,0,0,0,0, 0,0xa,0xb,0xc,0xd,0xe,0xf,0,0,0,0,0,0,0,0,0, 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0, 0,0xa,0xb,0xc,0xd,0xe,0xf,0,0,0,0,0,0,0,0,0 };
const char* pbegin = psz;
while (phexdigit[(unsigned char)*psz] || *psz == '0')
while (::HexDigit(*psz) != -1)
psz++;
psz--;
unsigned char* p1 = (unsigned char*)pn;
unsigned char* pend = p1 + WIDTH * 4;
while (psz >= pbegin && p1 < pend)
{
*p1 = phexdigit[(unsigned char)*psz--];
*p1 = ::HexDigit(*psz--);
if (psz >= pbegin)
{
*p1 |= (phexdigit[(unsigned char)*psz--] << 4);
*p1 |= ((unsigned char)::HexDigit(*psz--) << 4);
p1++;
}
}