feat(big): add 64-bit-centric ops

storm/CMakeLists.txt

@@ -3,6 +3,7 @@ check_cxx_compiler_flag(-Wno-invalid-offsetof HAS_NO_INVALID_OFFSETOF)
 
 file(GLOB STORM_SOURCES
     "*.cpp"
+    "big/*.cpp"
     "hash/*.cpp"
     "queue/*.cpp"
     "string/*.cpp"

storm/big/Ops.cpp

@@ -0,0 +1,24 @@
+#include "storm/big/Ops.hpp"
+
+uint32_t ExtractLowPart(uint64_t& value) {
+    auto low = static_cast<uint32_t>(value);
+    value >>= 32;
+
+    return low;
+}
+
+uint32_t ExtractLowPartSx(uint64_t& value) {
+    auto low = static_cast<uint32_t>(value);
+    value >>= 32;
+
+    if (value >= 0x80000000) {
+        reinterpret_cast<uint32_t*>(&value)[0] = value;
+        reinterpret_cast<uint32_t*>(&value)[1] = -1;
+    }
+
+    return low;
+}
+
+uint64_t MakeLarge(uint32_t low, uint32_t high) {
+    return low + (static_cast<uint64_t>(high) << 32);
+}

storm/big/Ops.hpp

@@ -0,0 +1,12 @@
+#ifndef STORM_BIG_OPS_HPP
+#define STORM_BIG_OPS_HPP
+
+#include <cstdint>
+
+uint32_t ExtractLowPart(uint64_t& value);
+
+uint32_t ExtractLowPartSx(uint64_t& value);
+
+uint64_t MakeLarge(uint32_t low, uint32_t high);
+
+#endif

test/Big.cpp

@@ -0,0 +1,68 @@
+#include "storm/big/Ops.hpp"
+#include "test/Test.hpp"
+
+TEST_CASE("ExtractLowPart", "[big]") {
+    SECTION("extracts low part of 0") {
+        uint64_t value = 0;
+        auto low = ExtractLowPart(value);
+
+        REQUIRE(low == 0);
+        REQUIRE(value == 0);
+    }
+
+    SECTION("extracts low part of 0x12345678") {
+        uint64_t value = 0x12345678;
+        auto low = ExtractLowPart(value);
+
+        REQUIRE(low == 0x12345678);
+        REQUIRE(value == 0);
+    }
+
+    SECTION("extracts low part of 0xAAAABBBBCCCCDDDD") {
+        uint64_t value = 0xAAAABBBBCCCCDDDD;
+        auto low = ExtractLowPart(value);
+
+        REQUIRE(low == 0xCCCCDDDD);
+        REQUIRE(value == 0xAAAABBBB);
+    }
+}
+
+TEST_CASE("ExtractLowPartSx", "[big]") {
+    SECTION("extracts low part of 0") {
+        uint64_t value = 0;
+        auto low = ExtractLowPartSx(value);
+
+        REQUIRE(low == 0);
+        REQUIRE(value == 0);
+    }
+
+    SECTION("extracts low part of 0x12345678") {
+        uint64_t value = 0x12345678;
+        auto low = ExtractLowPartSx(value);
+
+        REQUIRE(low == 0x12345678);
+        REQUIRE(value == 0);
+    }
+
+    SECTION("extracts low part of 0xAAAABBBBCCCCDDDD") {
+        uint64_t value = 0xAAAABBBBCCCCDDDD;
+        auto low = ExtractLowPartSx(value);
+
+        REQUIRE(low == 0xCCCCDDDD);
+        REQUIRE(value == 0xFFFFFFFFAAAABBBB);
+    }
+}
+
+TEST_CASE("MakeLarge", "[big]") {
+    SECTION("creates uint64_t out of 0xAABBCCDD and 0x11223344") {
+        uint64_t value = MakeLarge(0xAABBCCDD, 0x11223344);
+
+        REQUIRE(value == 0x11223344AABBCCDD);
+    }
+
+    SECTION("creates uint64_t out of 0 and 0x11223344") {
+        uint64_t value = MakeLarge(0x00000000, 0x11223344);
+
+        REQUIRE(value == 0x1122334400000000);
+    }
+}