Add string input interrupt from STDIN

README.md

@@ -89,22 +89,22 @@ There is currently no strict checking, so be careful.
 ## Directives
 
 - `DECLARE` declares the first label argument to equal the second, immediate
-value, argument and is used to declare a constant for the virtual machine.
+	value, argument and is used to declare a constant for the virtual machine.
 
 ### Operands
 
 - `addi` add the first to the second argument and store the result in the third
-argument
+	argument
 - `subi` subtract the first from the second argument and store the result in
-the third argument
+	the third argument
 - `divi` divide the first by the second argument and store the result in the
-third argument
+	third argument
 - `muli` multiply the first by the second argument and store the result in the
-third argument
+	third argument
 - `shli` shift left the first argument by the number of positions given by the
-second argument and store the result in the third argument
+	second argument and store the result in the third argument
 - `shri` shift right the first argument by the number of positions given by the
-second argument and store the result in the third argument
+	second argument and store the result in the third argument
 - `seti` set the first register argument to the second argument
 - `int` calls the interrupt specified by the first (integer) argument
 
@@ -112,15 +112,15 @@ second argument and store the result in the third argument
 
 - `jmp` jump to the label given by the first argument
 - `call` put the next statement to execute on the stack and jump to the label
-given by the first argument
+	given by the first argument
 - `ret` pop the the next statement to execute off the stack, e.g. returning to
-the next execution statement before calling `call`
+	the next execution statement before calling `call`
 - `lti` execute next statement if argument 1 is less than argument 2 else skip
-the next statement
+	the next statement
 - `gti` execute next statement if argument 1 is greater than argument 2 else
-skip the next statement
+	skip the next statement
 - `eqi` execute the next statement if argument 1 is equal to argument 2 else
-skip the next statement
+	skip the next statement
 
 ## Memory
 
@@ -137,5 +137,8 @@ the first argument
 	- `2` put value of register A as hexadecimal integer on stdout
 	- `3` put the string pointed at by register A for the amount of characters
 	defined by register B on stdout
-- [4..4] Input from STDIN
+- [4..5] Input from STDIN
-	- `4` get a single ASCII character from STDIN and store it in register A
+	- `4` get a single ASCII character from STDIN and store it in register A
+	- `5` get a string of a maximum length determined by register B and store it
+	in the address specified by register A. After execution register B will
+	contain the number of characters actually read.

bin/test.wasm

@@ -88,12 +88,22 @@ seti %A $900;
 seti %B $4;
 int $3;
 
-# Jump over the interrupt
+# Call a function
 call noop_function;
 
 # Echo a character
 int $4;
 int $0;
+
+seti %A $10; # newline
+int $0;
+
+# Echo a string
+seti %A $0;
+seti %B $10;
+int $5;
+int $3;
+
 exit;
 
 noop_function:

include/execute/error.hpp

@@ -39,6 +39,12 @@ namespace Execute
 		InterruptIndexOutOfRange(int const index);
 	};
 
+	class OutOfMemory : public RuntimeError
+	{
+	public:
+		OutOfMemory(int const memoryLocation, int const memorySize);
+	};
+
 	namespace Internal
 	{
 		class BadValueType : public RuntimeError

src/execute/error.cpp

@@ -41,6 +41,15 @@ namespace Execute
 		message += " is out of range";
 	}
 
+	OutOfMemory::OutOfMemory(int const memoryLocation, int const memorySize)
+	{
+		message = "Attempted interaction at memory location ";
+		message += std::to_string(memoryLocation);
+		message += " with size ";
+		message += std::to_string(memorySize);
+		message += " failed";
+	}
+
 	namespace Internal
 	{
 		BadValueType::BadValueType()

src/execute/interrupts.cpp

@@ -1,4 +1,5 @@
 #include <cstdio>
+#include <execute/error.hpp>
 #include <execute/interrupts.hpp>
 
 namespace Execute
@@ -18,6 +19,11 @@ namespace Execute
 			[](Execute::Registers & registers, std::vector<std::uint8_t> & memory)
 			{
 				unsigned const end = registers.A + registers.B;
+				if (end >= memory.size())
+				{
+					throw OutOfMemory(registers.A, registers.B);
+				}
+
 				for(unsigned i = registers.A; i < end; ++i)
 				{
 					std::putc(memory[i], stdout);
@@ -29,7 +35,49 @@ namespace Execute
 			[](Execute::Registers & registers, std::vector<std::uint8_t> & memory)
 			{
 				registers.A = std::getchar();
-			}
+				if (registers.A == '\n')
+				{
+					return;
+				}
+
+				while(std::getchar() != '\n');
+			},
+			// 11 get string from STDIN
+			[](Execute::Registers & registers, std::vector<std::uint8_t> & memory)
+			{
+				if (registers.B <= 0)
+				{
+					registers.B = 0;
+					return;
+				}
+
+				if (registers.A < 0 || static_cast<unsigned>(registers.A + registers.B) >= memory.size())
+				{
+					throw OutOfMemory(registers.A, registers.B);
+				}
+
+				int charactersRead = 0;
+				bool newlineRead = false;
+				while(charactersRead < registers.B)
+				{
+					char result = std::getchar();
+					if (result == '\n')
+					{
+						newlineRead = true;
+						break;
+					}
+
+					memory[registers.A + charactersRead] = result;
+					++charactersRead;
+				}
+
+				registers.B = charactersRead;
+
+				if (!newlineRead)
+				{
+					while(std::getchar() != '\n');
+				}
+			},
 		};
 	}
 }