From 6a88f936198313241f464032dbf70f47ea5e7622 Mon Sep 17 00:00:00 2001
From: Adam Heinermann <aheinerm@gmail.com>
Date: Sun, 17 Nov 2024 03:17:16 -0800
Subject: [PATCH] feat(big): implement ToStream and EncodeDataBytes ops

---
 storm/big/Ops.cpp | 15 ++++++++++++++
 storm/big/Ops.hpp |  4 ++++
 test/big/Ops.cpp  | 50 ++++++++++++++++++++++++++++++++++++++++++++++-
 3 files changed, 68 insertions(+), 1 deletion(-)

diff --git a/storm/big/Ops.cpp b/storm/big/Ops.cpp
index a835267..fe636b5 100644
--- a/storm/big/Ops.cpp
+++ b/storm/big/Ops.cpp
@@ -131,6 +131,15 @@ void Div(BigBuffer& a, BigBuffer& b, const BigBuffer& c, const BigBuffer& d, Big
     stack.Free(allocCount);
 }
 
+void EncodeDataBytes(TSGrowableArray<uint8_t>& output, uint32_t value) {
+    uint32_t v = value;
+    while (v != 0) {
+        *output.New() = v % 255u;
+        v /= 255u;
+    }
+    *output.New() = 255;
+}
+
 uint32_t ExtractLowPart(uint64_t& value) {
     auto low = static_cast<uint32_t>(value);
     value >>= 32;
@@ -467,3 +476,9 @@ void ToBinary(TSGrowableArray<uint8_t>& output, const BigBuffer& buffer) {
     output.SetCount(0);
     ToBinaryAppend(output, buffer);
 }
+
+void ToStream(TSGrowableArray<uint8_t>& output, const BigBuffer& buffer) {
+    ToBinary(output, buffer);
+    EncodeDataBytes(output, output.Count());
+    ToBinaryAppend(output, buffer);
+}
diff --git a/storm/big/Ops.hpp b/storm/big/Ops.hpp
index 10ec817..3743078 100644
--- a/storm/big/Ops.hpp
+++ b/storm/big/Ops.hpp
@@ -17,6 +17,8 @@ void Div(BigBuffer& a, uint32_t* b, const BigBuffer& c, uint64_t d);
 
 void Div(BigBuffer& a, BigBuffer& b, const BigBuffer& c, const BigBuffer& d, BigStack& stack);
 
+void EncodeDataBytes(TSGrowableArray<uint8_t>& output, uint32_t value);
+
 uint32_t ExtractLowPart(uint64_t& value);
 
 uint32_t ExtractLowPartLargeSum(uint64_t& value, uint64_t add);
@@ -71,4 +73,6 @@ void Sub(BigBuffer& a, const BigBuffer& b, uint32_t c);
 
 void ToBinary(TSGrowableArray<uint8_t>& output, const BigBuffer& buffer);
 
+void ToStream(TSGrowableArray<uint8_t>& output, const BigBuffer& buffer);
+
 #endif
diff --git a/test/big/Ops.cpp b/test/big/Ops.cpp
index c7c04ba..935c060 100644
--- a/test/big/Ops.cpp
+++ b/test/big/Ops.cpp
@@ -1,6 +1,7 @@
 #include "storm/Big.hpp"
 #include "storm/big/Ops.hpp"
 #include "test/Test.hpp"
+#include <vector>
 
 TEST_CASE("Add", "[big]") {
     BigDataTest a, b;
@@ -280,6 +281,28 @@ TEST_CASE("Div", "[big]") {
     }
 }
 
+TEST_CASE("EncodeDataBytes", "[big]") {
+    struct EncodeTestCase {
+        uint32_t input;
+        std::vector<uint8_t> output;
+    };
+
+    SECTION("encodes values to array") {
+        auto v = GENERATE(
+            EncodeTestCase{ 0, { 255 } },
+            EncodeTestCase{ 1, { 1, 255 } },
+            EncodeTestCase{ 255, { 0, 1, 255 } },
+            EncodeTestCase{ UINT32_MAX, { 0, 4, 6, 4, 1, 255 } }
+        );
+
+        TSGrowableArray<uint8_t> arr;
+        EncodeDataBytes(arr, v.input);
+
+        CHECK(arr.Count() == v.output.size());
+        CHECK(std::vector<uint8_t>(arr.m_data, arr.m_data + arr.Count()) == v.output);
+    }
+}
+
 TEST_CASE("ExtractLowPart", "[big]") {
     SECTION("extracts low part of 0") {
         uint64_t value = 0;
@@ -1045,5 +1068,30 @@ TEST_CASE("Sub", "[big]") {
         CHECK(a->Primary()[0] == 0xDB975320);
         CHECK(a->Primary()[1] == 0xECA8641F);
     }
-
+}
+
+
+TEST_CASE("ToStream", "[big]") {
+    BigDataTest a;
+
+    struct ToStreamTestCase {
+        uint64_t input;
+        std::vector<uint8_t> output;
+    };
+
+    SECTION("streams buffers to array") {
+        auto v = GENERATE(
+            ToStreamTestCase{ 0, { 255 } },
+            ToStreamTestCase{ 1, { 1, 1, 255, 1 } },
+            ToStreamTestCase{ 255, { 0xFF, 1, 255, 0xFF } },
+            ToStreamTestCase{ UINT32_MAX, { 0xFF, 0xFF, 0xFF, 0xFF, 4, 255, 0xFF, 0xFF, 0xFF, 0xFF } },
+            ToStreamTestCase{ 0x123456789ABCDEF0, { 0xF0, 0xDE, 0xBC, 0x9A, 0x78, 0x56, 0x34, 0x12, 8, 255, 0xF0, 0xDE, 0xBC, 0x9A, 0x78, 0x56, 0x34, 0x12 } }
+        );
+
+        TSGrowableArray<uint8_t> arr;
+        SBigFromStr(a, std::to_string(v.input).c_str());
+        ToStream(arr, a->Primary());
+
+        CHECK(std::vector<uint8_t>(arr.m_data, arr.m_data + arr.Count()) == v.output);
+    }
 }