From 3e6cbdeda83c2955b9f40c6995c76cce49cb33d7 Mon Sep 17 00:00:00 2001
From: m8pple <dt10@imperial.ac.uk>
Date: Mon, 20 Oct 2014 13:30:29 +0100
Subject: Very basic skeleton from the classes.

---
 src/eie2ugs/mips_cpu.c    | 85 +++++++++++++++++++++++++++++++++++++++++++++++
 src/eie2ugs/test_mips.cpp | 47 ++++++++++++++++++++++++++
 2 files changed, 132 insertions(+)
 create mode 100644 src/eie2ugs/mips_cpu.c
 create mode 100644 src/eie2ugs/test_mips.cpp

diff --git a/src/eie2ugs/mips_cpu.c b/src/eie2ugs/mips_cpu.c
new file mode 100644
index 0000000..7138bcd
--- /dev/null
+++ b/src/eie2ugs/mips_cpu.c
@@ -0,0 +1,85 @@
+#include "mips.h"
+
+#include <stdlib.h>
+
+struct mips_cpu_impl{
+
+	uint32_t pc;
+	uint32_t pcN;
+	uint32_t regs[32];
+
+	mips_mem_h mem;
+};
+
+mips_cpu_h mips_cpu_create(mips_mem_h mem)
+{
+	unsigned i;
+	mips_cpu_h res=(mips_cpu_h)malloc(sizeof(struct mips_cpu_impl));
+
+	res->mem=mem;
+
+	res->pc=0;
+	res->pcN=4;	// NOTE: why does this make sense?
+
+	for( i=0;i<32;i++){
+		res->regs[i]=0;
+	}
+
+	return res;
+}
+
+void mips_cpu_free(mips_cpu_h state)
+{
+	free(state);
+}
+
+mips_error mips_cpu_get_register(
+	mips_cpu_h state,	//!< Valid (non-empty) handle to a CPU
+	unsigned index,		//!< Index from 0 to 31
+	uint32_t *value		//!< Where to write the value to
+)
+{
+	if(state==0)
+		return mips_ErrorInvalidHandle;
+	if(index>=32)
+		return mips_ErrorInvalidArgument;
+	if(value==0)
+		return mips_ErrorInvalidArgument;
+
+	*value = state->regs[index];
+	return mips_Success;
+}
+
+/*! Modifies one of the 32 general purpose MIPS registers. */
+mips_error mips_cpu_set_register(
+	mips_cpu_h state,	//!< Valid (non-empty) handle to a CPU
+	unsigned index,		//!< Index from 0 to 31
+	uint32_t value		//!< New value to write into register file
+)
+{
+	if(state==0)
+		return mips_ErrorInvalidHandle;
+	if(index>=32)
+		return mips_ErrorInvalidArgument;
+
+	// TODO : What about register zero?
+	state->regs[index]=value;
+
+	return mips_Success;
+}
+
+mips_error mips_cpu_step(mips_cpu_h state)
+{
+	uint32_t pc=state->pc;
+
+	if(state==0)
+		return mips_ErrorInvalidHandle;
+
+	//TODO: Here is where the magic happens
+	// - Fetch the instruction from memory (mips_mem_read)
+	// - Decode the instruction (is it R, I, J)?
+	// - Execute the instruction (do maths, access memory, ...)
+	// - Writeback the results (update registers, advance pc)
+
+	return mips_ErrorNotImplemented;
+}
diff --git a/src/eie2ugs/test_mips.cpp b/src/eie2ugs/test_mips.cpp
new file mode 100644
index 0000000..e9a6955
--- /dev/null
+++ b/src/eie2ugs/test_mips.cpp
@@ -0,0 +1,47 @@
+#include "mips_test.h"
+
+int main()
+{
+	mips_mem_h mem=mips_mem_create_ram(
+		1<<20,
+		4
+		);
+
+	mips_cpu_h cpu=mips_cpu_create(mem);
+
+	mips_test_begin_suite();
+
+	int testId=mips_test_begin_test("and");
+	int passed=0;
+
+	
+	mips_error err = mips_cpu_set_register(cpu, 8, 0x0000FFFFul);
+	if(err==0)
+		err = mips_cpu_set_register(cpu, 9, 0x00FFFF00ul);
+
+	// and $10, $8, $9
+
+	// TODO : work out the bit-wise encoding for the instruction.
+
+	// TODO : Write it into mempory at a known address
+
+	// TODO : Make sure the program-counter is at that address
+
+	if(err==0)
+		err=mips_cpu_step(cpu);
+
+	uint32_t got;
+	if(err==0)
+		err = (mips_error)(err | mips_cpu_get_register(cpu, 10, &got));
+
+	passed = (err == mips_Success) && (got==0x0000FF00);
+
+	mips_test_end_test(testId, passed, NULL);
+
+	mips_test_end_suite();
+
+	mips_cpu_free(cpu);
+	mips_mem_free(mem);
+
+	return 0;
+}
\ No newline at end of file
-- 
cgit