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-rw-r--r--src/main.cpp54
-rw-r--r--src/main.h17
-rw-r--r--src/test/compress_tests.cpp62
3 files changed, 130 insertions, 3 deletions
diff --git a/src/main.cpp b/src/main.cpp
index 43bb4b1793..ed677f31c8 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -4058,3 +4058,57 @@ void GenerateBitcoins(bool fGenerate, CWallet* pwallet)
}
}
}
+
+// Amount compression:
+// * If the amount is 0, output 0
+// * first, divide the amount (in base units) by the largest power of 10 possible; call the exponent e (e is max 9)
+// * if e<9, the last digit of the resulting number cannot be 0; store it as d, and drop it (divide by 10)
+// * call the result n
+// * output 1 + 10*(9*n + d - 1) + e
+// * if e==9, we only know the resulting number is not zero, so output 1 + 10*(n - 1) + 9
+// (this is decodable, as d is in [1-9] and e is in [0-9])
+
+uint64 CTxOutCompressor::CompressAmount(uint64 n)
+{
+ if (n == 0)
+ return 0;
+ int e = 0;
+ while (((n % 10) == 0) && e < 9) {
+ n /= 10;
+ e++;
+ }
+ if (e < 9) {
+ int d = (n % 10);
+ assert(d >= 1 && d <= 9);
+ n /= 10;
+ return 1 + (n*9 + d - 1)*10 + e;
+ } else {
+ return 1 + (n - 1)*10 + 9;
+ }
+}
+
+uint64 CTxOutCompressor::DecompressAmount(uint64 x)
+{
+ // x = 0 OR x = 1+10*(9*n + d - 1) + e OR x = 1+10*(n - 1) + 9
+ if (x == 0)
+ return 0;
+ x--;
+ // x = 10*(9*n + d - 1) + e
+ int e = x % 10;
+ x /= 10;
+ uint64 n = 0;
+ if (e < 9) {
+ // x = 9*n + d - 1
+ int d = (x % 9) + 1;
+ x /= 9;
+ // x = n
+ n = x*10 + d;
+ } else {
+ n = x+1;
+ }
+ while (e) {
+ n *= 10;
+ e--;
+ }
+ return n;
+}
diff --git a/src/main.h b/src/main.h
index 1af781f45c..4286880c9f 100644
--- a/src/main.h
+++ b/src/main.h
@@ -652,14 +652,25 @@ class CTxOutCompressor
{
private:
CTxOut &txout;
+
public:
+ static uint64 CompressAmount(uint64 nAmount);
+ static uint64 DecompressAmount(uint64 nAmount);
+
CTxOutCompressor(CTxOut &txoutIn) : txout(txoutIn) { }
- IMPLEMENT_SERIALIZE(
- READWRITE(VARINT(txout.nValue));
+ IMPLEMENT_SERIALIZE(({
+ if (!fRead) {
+ uint64 nVal = CompressAmount(txout.nValue);
+ READWRITE(VARINT(nVal));
+ } else {
+ uint64 nVal = 0;
+ READWRITE(VARINT(nVal));
+ txout.nValue = DecompressAmount(nVal);
+ }
CScriptCompressor cscript(REF(txout.scriptPubKey));
READWRITE(cscript);
- )
+ });)
};
diff --git a/src/test/compress_tests.cpp b/src/test/compress_tests.cpp
new file mode 100644
index 0000000000..71b86bcb41
--- /dev/null
+++ b/src/test/compress_tests.cpp
@@ -0,0 +1,62 @@
+#include <boost/test/unit_test.hpp>
+
+#include <string>
+#include <vector>
+
+#include "main.h"
+
+// amounts 0.00000001 .. 0.00100000
+#define NUM_MULTIPLES_UNIT 100000
+
+// amounts 0.01 .. 100.00
+#define NUM_MULTIPLES_CENT 10000
+
+// amounts 1 .. 10000
+#define NUM_MULTIPLES_1BTC 10000
+
+// amounts 50 .. 21000000
+#define NUM_MULTIPLES_50BTC 420000
+
+using namespace std;
+
+BOOST_AUTO_TEST_SUITE(compress_tests)
+
+bool static TestEncode(uint64 in) {
+ return in == CTxOutCompressor::DecompressAmount(CTxOutCompressor::CompressAmount(in));
+}
+
+bool static TestDecode(uint64 in) {
+ return in == CTxOutCompressor::CompressAmount(CTxOutCompressor::DecompressAmount(in));
+}
+
+bool static TestPair(uint64 dec, uint64 enc) {
+ return CTxOutCompressor::CompressAmount(dec) == enc &&
+ CTxOutCompressor::DecompressAmount(enc) == dec;
+}
+
+BOOST_AUTO_TEST_CASE(compress_amounts)
+{
+ BOOST_CHECK(TestPair( 0, 0x0));
+ BOOST_CHECK(TestPair( 1, 0x1));
+ BOOST_CHECK(TestPair( CENT, 0x7));
+ BOOST_CHECK(TestPair( COIN, 0x9));
+ BOOST_CHECK(TestPair( 50*COIN, 0x32));
+ BOOST_CHECK(TestPair(21000000*COIN, 0x1406f40));
+
+ for (uint64 i = 1; i <= NUM_MULTIPLES_UNIT; i++)
+ BOOST_CHECK(TestEncode(i));
+
+ for (uint64 i = 1; i <= NUM_MULTIPLES_CENT; i++)
+ BOOST_CHECK(TestEncode(i * CENT));
+
+ for (uint64 i = 1; i <= NUM_MULTIPLES_1BTC; i++)
+ BOOST_CHECK(TestEncode(i * COIN));
+
+ for (uint64 i = 1; i <= NUM_MULTIPLES_50BTC; i++)
+ BOOST_CHECK(TestEncode(i * 50 * COIN));
+
+ for (uint64 i = 0; i < 100000; i++)
+ BOOST_CHECK(TestDecode(i));
+}
+
+BOOST_AUTO_TEST_SUITE_END()