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Generalize ConvertBits

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This commit is contained in:
Pieter Wuille
2017-11-22 17:04:48 -08:00
committed by Jack Grigg
parent 6b759fb092
commit ac70f76c5d
2 changed files with 9 additions and 9 deletions
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12
src/test/convertbits_tests.cpp
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@@ -16,8 +16,8 @@ BOOST_AUTO_TEST_CASE(convertbits_deterministic)
std::vector<unsigned char> input(32, i); std::vector<unsigned char> input(32, i);
std::vector<unsigned char> data; std::vector<unsigned char> data;
std::vector<unsigned char> output; std::vector<unsigned char> output;
ConvertBits<8, 5, true>(data, input.begin(), input.end()); ConvertBits<8, 5, true>([&](unsigned char c) { data.push_back(c); }, input.begin(), input.end());
ConvertBits<5, 8, false>(output, data.begin(), data.end()); ConvertBits<5, 8, false>([&](unsigned char c) { output.push_back(c); }, data.begin(), data.end());
BOOST_CHECK_EQUAL(data.size(), 52); BOOST_CHECK_EQUAL(data.size(), 52);
BOOST_CHECK_EQUAL(output.size(), 32); BOOST_CHECK_EQUAL(output.size(), 32);
BOOST_CHECK(input == output); BOOST_CHECK(input == output);
@@ -27,8 +27,8 @@ BOOST_AUTO_TEST_CASE(convertbits_deterministic)
std::vector<unsigned char> input(43, i); std::vector<unsigned char> input(43, i);
std::vector<unsigned char> data; std::vector<unsigned char> data;
std::vector<unsigned char> output; std::vector<unsigned char> output;
ConvertBits<8, 5, true>(data, input.begin(), input.end()); ConvertBits<8, 5, true>([&](unsigned char c) { data.push_back(c); }, input.begin(), input.end());
ConvertBits<5, 8, false>(output, data.begin(), data.end()); ConvertBits<5, 8, false>([&](unsigned char c) { output.push_back(c); }, data.begin(), data.end());
BOOST_CHECK_EQUAL(data.size(), 69); BOOST_CHECK_EQUAL(data.size(), 69);
BOOST_CHECK_EQUAL(output.size(), 43); BOOST_CHECK_EQUAL(output.size(), 43);
BOOST_CHECK(input == output); BOOST_CHECK(input == output);
@@ -41,8 +41,8 @@ BOOST_AUTO_TEST_CASE(convertbits_random)
auto input = libzcash::random_uint256(); auto input = libzcash::random_uint256();
std::vector<unsigned char> data; std::vector<unsigned char> data;
std::vector<unsigned char> output; std::vector<unsigned char> output;
ConvertBits<8, 5, true>(data, input.begin(), input.end()); ConvertBits<8, 5, true>([&](unsigned char c) { data.push_back(c); }, input.begin(), input.end());
ConvertBits<5, 8, false>(output, data.begin(), data.end()); ConvertBits<5, 8, false>([&](unsigned char c) { output.push_back(c); }, data.begin(), data.end());
BOOST_CHECK_EQUAL(data.size(), 52); BOOST_CHECK_EQUAL(data.size(), 52);
BOOST_CHECK_EQUAL(output.size(), 32); BOOST_CHECK_EQUAL(output.size(), 32);
BOOST_CHECK(input == uint256(output)); BOOST_CHECK(input == uint256(output));

6
src/utilstrencodings.h
View File

@@ -135,7 +135,7 @@ bool ParseFixedPoint(const std::string &val, int decimals, int64_t *amount_out);
/** Convert from one power-of-2 number base to another. */ /** Convert from one power-of-2 number base to another. */
template<int frombits, int tobits, bool pad, typename O, typename I> template<int frombits, int tobits, bool pad, typename O, typename I>
bool ConvertBits(O& out, I it, I end) { bool ConvertBits(const O& outfn, I it, I end) {
size_t acc = 0; size_t acc = 0;
size_t bits = 0; size_t bits = 0;
constexpr size_t maxv = (1 << tobits) - 1; constexpr size_t maxv = (1 << tobits) - 1;
@@ -145,12 +145,12 @@ bool ConvertBits(O& out, I it, I end) {
bits += frombits; bits += frombits;
while (bits >= tobits) { while (bits >= tobits) {
bits -= tobits; bits -= tobits;
out.push_back((acc >> bits) & maxv); outfn((acc >> bits) & maxv);
} }
++it; ++it;
} }
if (pad) { if (pad) {
if (bits) out.push_back((acc << (tobits - bits)) & maxv); if (bits) outfn((acc << (tobits - bits)) & maxv);
} else if (bits >= frombits || ((acc << (tobits - bits)) & maxv)) { } else if (bits >= frombits || ((acc << (tobits - bits)) & maxv)) {
return false; return false;
} }