From aad7f751dddfcbb609423b2ca7bcd1395459ff69 Mon Sep 17 00:00:00 2001
From: fallenoak <git@fallenoak.me>
Date: Tue, 31 Jan 2023 22:17:51 -0600
Subject: [PATCH] feat(big): add Add

---
 storm/big/Ops.cpp | 11 ++++++++
 storm/big/Ops.hpp |  2 ++
 test/Big.cpp      | 66 +++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 79 insertions(+)

diff --git a/storm/big/Ops.cpp b/storm/big/Ops.cpp
index 4df9cb6..513c9bc 100644
--- a/storm/big/Ops.cpp
+++ b/storm/big/Ops.cpp
@@ -1,5 +1,16 @@
 #include "storm/big/Ops.hpp"
 
+void Add(BigBuffer& a, const BigBuffer& b, uint32_t c) {
+    uint64_t carry = c;
+    uint32_t i = 0;
+    for (i = 0; carry || b.IsUsed(i); i++) {
+        carry += b[i];
+        a[i] = ExtractLowPart(carry);
+    }
+
+    a.SetCount(i);
+}
+
 void Add(BigBuffer& a, const BigBuffer& b, const BigBuffer& c) {
     uint64_t carry = 0;
     uint32_t i = 0;
diff --git a/storm/big/Ops.hpp b/storm/big/Ops.hpp
index 404c61b..7d67192 100644
--- a/storm/big/Ops.hpp
+++ b/storm/big/Ops.hpp
@@ -5,6 +5,8 @@
 #include "storm/big/BigStack.hpp"
 #include <cstdint>
 
+void Add(BigBuffer& a, const BigBuffer& b, uint32_t c);
+
 void Add(BigBuffer& a, const BigBuffer& b, const BigBuffer& c);
 
 uint32_t ExtractLowPart(uint64_t& value);
diff --git a/test/Big.cpp b/test/Big.cpp
index 7afbbe0..6126076 100644
--- a/test/Big.cpp
+++ b/test/Big.cpp
@@ -2,6 +2,72 @@
 #include "storm/big/Ops.hpp"
 #include "test/Test.hpp"
 
+TEST_CASE("Add", "[big]") {
+    SECTION("adds 0 and 1") {
+        BigData* a;
+        SBigNew(&a);
+
+        BigData* b;
+        SBigNew(&b);
+        SBigFromUnsigned(b, 0);
+
+        uint64_t c = 1;
+
+        Add(a->Primary(), b->Primary(), c);
+
+        a->Primary().Trim();
+
+        CHECK(a->Primary().Count() == 1);
+        CHECK(a->Primary()[0] == 1);
+
+        SBigDel(a);
+        SBigDel(b);
+    }
+
+    SECTION("adds 2 and 4") {
+        BigData* a;
+        SBigNew(&a);
+
+        BigData* b;
+        SBigNew(&b);
+        SBigFromUnsigned(b, 2);
+
+        uint64_t c = 4;
+
+        Add(a->Primary(), b->Primary(), c);
+
+        a->Primary().Trim();
+
+        CHECK(a->Primary().Count() == 1);
+        CHECK(a->Primary()[0] == 6);
+
+        SBigDel(a);
+        SBigDel(b);
+    }
+
+    SECTION("adds 0xFFFFFFFF and 0xCCCCCCCC") {
+        BigData* a;
+        SBigNew(&a);
+
+        BigData* b;
+        SBigNew(&b);
+        SBigFromUnsigned(b, 0xFFFFFFFF);
+
+        uint64_t c = 0xCCCCCCCC;
+
+        Add(a->Primary(), b->Primary(), c);
+
+        a->Primary().Trim();
+
+        CHECK(a->Primary().Count() == 2);
+        CHECK(a->Primary()[0] == 0xCCCCCCCB);
+        CHECK(a->Primary()[1] == 0x1);
+
+        SBigDel(a);
+        SBigDel(b);
+    }
+}
+
 TEST_CASE("ExtractLowPart", "[big]") {
     SECTION("extracts low part of 0") {
         uint64_t value = 0;