From b84cf62d6bd3a9caa8a9a7f1dcd427418170aed9 Mon Sep 17 00:00:00 2001
From: Christian <c@ethdev.com>
Date: Tue, 3 Mar 2015 17:55:28 +0100
Subject: Index access for calldata arrays.

---
 LValue.cpp | 59 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 58 insertions(+), 1 deletion(-)

(limited to 'LValue.cpp')

diff --git a/LValue.cpp b/LValue.cpp
index 452ca1c7..f5730020 100644
--- a/LValue.cpp
+++ b/LValue.cpp
@@ -232,6 +232,64 @@ void StorageItem::setToZero(SourceLocation const&, bool _removeReference) const
 	}
 }
 
+/// Used in StorageByteArrayElement
+static IntegerType byteType(8, IntegerType::Modifier::Hash);
+
+StorageByteArrayElement::StorageByteArrayElement(CompilerContext& _compilerContext):
+	LValue(_compilerContext, byteType)
+{
+}
+
+void StorageByteArrayElement::retrieveValue(SourceLocation const&, bool _remove) const
+{
+	// stack: ref bytenr
+	if (_remove)
+		m_context << eth::Instruction::SWAP1 << eth::Instruction::SLOAD
+			<< eth::Instruction::SWAP1 << eth::Instruction::BYTE;
+	else
+		m_context << eth::Instruction::DUP2 << eth::Instruction::SLOAD
+			<< eth::Instruction::DUP2 << eth::Instruction::BYTE;
+}
+
+void StorageByteArrayElement::storeValue(Type const&, SourceLocation const&, bool _move) const
+{
+	//@todo optimize this
+
+	// stack: value ref bytenr
+	m_context << u256(31) << eth::Instruction::SUB << u256(0x100) << eth::Instruction::EXP;
+	// stack: value ref (1<<(8*(31-bytenr)))
+	m_context << eth::Instruction::DUP2 << eth::Instruction::SLOAD;
+	// stack: value ref (1<<(8*(31-bytenr))) old_full_value
+	// clear byte in old value
+	m_context << eth::Instruction::DUP2 << u256(0xff) << eth::Instruction::MUL
+		<< eth::Instruction::NOT << eth::Instruction::AND;
+	// stack: value ref (1<<(32-bytenr)) old_full_value_with_cleared_byte
+	m_context << eth::Instruction::SWAP1 << eth::Instruction::DUP4 << eth::Instruction::MUL
+		<< eth::Instruction::OR;
+	// stack: value ref new_full_value
+	m_context << eth::Instruction::SWAP1 << eth::Instruction::SSTORE;
+	if (_move)
+		m_context << eth::Instruction::POP;
+}
+
+void StorageByteArrayElement::setToZero(SourceLocation const&, bool _removeReference) const
+{
+	// stack: ref bytenr
+	if (!_removeReference)
+		m_context << eth::Instruction::SWAP1 << eth::Instruction::DUP2;
+	m_context << u256(31) << eth::Instruction::SUB << u256(0x100) << eth::Instruction::EXP;
+	// stack: ref (1<<(8*(31-bytenr)))
+	m_context << eth::Instruction::DUP2 << eth::Instruction::SLOAD;
+	// stack: ref (1<<(8*(31-bytenr))) old_full_value
+	// clear byte in old value
+	m_context << eth::Instruction::SWAP1 << u256(0xff) << eth::Instruction::MUL << eth::Instruction::AND;
+	// stack: ref old_full_value_with_cleared_byte
+	m_context << eth::Instruction::SWAP1 << eth::Instruction::SSTORE;
+	if (!_removeReference)
+		m_context << eth::Instruction::SWAP1;
+	else
+		m_context << eth::Instruction::POP;
+}
 
 StorageArrayLength::StorageArrayLength(CompilerContext& _compilerContext, const ArrayType& _arrayType):
 	LValue(_compilerContext, *_arrayType.getMemberType("length")),
@@ -262,4 +320,3 @@ void StorageArrayLength::setToZero(SourceLocation const&, bool _removeReference)
 		m_context << eth::Instruction::DUP1;
 	ArrayUtils(m_context).clearDynamicArray(m_arrayType);
 }
-
-- 
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