feat(big): add SBigFromStr

storm/Big.cpp

@@ -48,6 +48,10 @@ void SBigFromBinary(BigData* num, const void* data, uint32_t bytes) {
     FromBinary(num->Primary(), data, bytes);
 }
 
+void SBigFromStr(BigData* num, const char *str) {
+    FromStr(num->Primary(), str);
+}
+
 void SBigFromUnsigned(BigData* num, uint32_t val) {
     FromUnsigned(num->Primary(), val);
 }

storm/Big.hpp

@@ -20,6 +20,8 @@ void SBigDel(BigData* num);
 
 void SBigFromBinary(BigData* num, const void* data, uint32_t bytes);
 
+void SBigFromStr(BigData* num, const char* str);
+
 void SBigFromUnsigned(BigData* num, uint32_t val);
 
 void SBigMod(BigData* a, BigData* b, BigData* c);

storm/big/Ops.cpp

@@ -167,6 +167,14 @@ void FromBinary(BigBuffer& buffer, const void* data, uint32_t bytes) {
     }
 }
 
+void FromStr(BigBuffer& buffer, const char* str) {
+    SetZero(buffer);
+    for (; *str; str++) {
+        Mul(buffer, buffer, 10);
+        Add(buffer, buffer, *str - '0');
+    }
+}
+
 void FromUnsigned(BigBuffer& buffer, uint32_t value) {
     buffer[0] = value;
     buffer.SetCount(1);

storm/big/Ops.hpp

@@ -25,6 +25,8 @@ uint32_t ExtractLowPartSx(uint64_t& value);
 
 void FromBinary(BigBuffer& buffer, const void* value, uint32_t bytes);
 
+void FromStr(BigBuffer& buffer, const char* str);
+
 void FromUnsigned(BigBuffer& buffer, uint32_t value);
 
 uint32_t HighBitPos(const BigBuffer& buffer);

test/Big.cpp

@@ -281,6 +281,32 @@ TEST_CASE("SBigFromBinary", "[big]") {
     }
 }
 
+TEST_CASE("SBigFromStr", "[big]") {
+    BigDataTest num;
+
+    SECTION("with empty string") {
+        SBigFromStr(num, "");
+
+        CHECK(num->Primary().Count() == 0);
+    }
+
+    SECTION("with string containing numbers") {
+        SBigFromStr(num, "123456");
+
+        CHECK(num->Primary().Count() == 1);
+        CHECK(num->Primary()[0] == 123456);
+    }
+
+    SECTION("with string containing letters (original bug)") {
+        SBigFromStr(num, "ABC");
+
+        const unsigned int expected_num = ('A' - '0') * 100 + ('B' - '0') * 10 + ('C' - '0');
+
+        CHECK(num->Primary().Count() == 1);
+        CHECK(num->Primary()[0] == expected_num);
+    }
+}
+
 TEST_CASE("SBigFromUnsigned", "[big]") {
     SECTION("creates bigdata from 0") {
         BigData* num;