add copyByteToUnitAsLE and copyUnitToByteAsLE

_

1 files changed, 53 insertions, 2 deletions

diff --git a/src/fp.cpp b/src/fp.cpp
index 490699e..ed6601d 100644
--- a/src/fp.cpp
+++ b/src/fp.cpp
@@ -1,6 +1,7 @@
 #include <mcl/op.hpp>
 #include <mcl/util.hpp>
 #include <cybozu/crypto.hpp>
+#include <cybozu/endian.hpp>
 #include "conversion.hpp"
 #include "fp_generator.hpp"
 #include "low_func.hpp"
@@ -36,6 +37,22 @@ void Op::destroyFpGenerator(FpGenerator *)
 }
 #endif
 
+inline void setUnitAsLE(void *p, Unit x)
+{
+#if CYBOZU_OS_BIT == 32
+	cybozu::Set32bitAsLE(p, x);
+#else
+	cybozu::Set64bitAsLE(p, x);
+#endif
+}
+inline Unit getUnitAsLE(const void *p)
+{
+#if CYBOZU_OS_BIT == 32
+	return cybozu::Get32bitAsLE(p);
+#else
+	return cybozu::Get64bitAsLE(p);
+#endif
+}
 /*
 	use prefix if base conflicts with prefix
 */
@@ -468,6 +485,38 @@ void arrayToStr(std::string& str, const Unit *x, size_t n, int base, bool withPr
 	}
 }
 
+void copyUnitToByteAsLE(void *dst, const Unit *src, size_t byteSize)
+{
+	uint8_t *p = reinterpret_cast<uint8_t*>(dst);
+	while (byteSize >= sizeof(Unit)) {
+		setUnitAsLE(p, *src++);
+		p += sizeof(Unit);
+		byteSize -= sizeof(Unit);
+	}
+	if (byteSize == 0) return;
+	Unit x = *src;
+	while (byteSize) {
+		*p++ = static_cast<uint8_t>(x);
+		x >>= 8;
+		byteSize--;
+	}
+}
+
+void copyByteToUnitAsLE(Unit *dst, const void *src, size_t byteSize)
+{
+	const uint8_t *p = reinterpret_cast<const uint8_t*>(src);
+	while (byteSize >= sizeof(Unit)) {
+		*dst++ = getUnitAsLE(p);
+		p += sizeof(Unit);
+		byteSize -= sizeof(Unit);
+	}
+	if (byteSize == 0) return;
+	Unit x = 0;
+	for (size_t i = 0; i < byteSize; i++) {
+		x |= Unit(p[i]) << (i * 8);
+	}
+	*dst = x;
+}
 void copyAndMask(Unit *y, const void *x, size_t xByteSize, const Op& op, bool doMask)
 {
 	const size_t fpByteSize = sizeof(Unit) * op.N;
@@ -475,8 +524,10 @@ void copyAndMask(Unit *y, const void *x, size_t xByteSize, const Op& op, bool do
 		if (!doMask) throw cybozu::Exception("fp:copyAndMask:bad size") << xByteSize << fpByteSize;
 		xByteSize = fpByteSize;
 	}
-	memcpy(y, x, xByteSize);
-	memset((char *)y + xByteSize, 0, fpByteSize - xByteSize);
+	copyByteToUnitAsLE(y, x, xByteSize);
+	for (size_t i = (xByteSize + sizeof(Unit) - 1) / sizeof(Unit); i < op.N; i++) {
+		y[i] = 0;
+	}
 	if (!doMask) {
 		if (isGreaterOrEqualArray(y, op.p, op.N)) throw cybozu::Exception("fp:copyAndMask:large x");
 		return;