Initial Commit

7 files changed, 419 insertions, 0 deletions

diff --git a/README.md b/README.md
new file mode 100644
index 0000000..370e3e6
--- /dev/null
+++ b/README.md
@@ -0,0 +1,70 @@
+# QDME - Quick and Dirty MIPS Emulator
+
+## Intro
+
+QDME is a simple MIPS emulator written in C. Currently the binary file must be
+manually created, eventually this will change.
+
+## Instructions
+|Instruction|Type|Action|
+|-----------|----|------|
+|add        |R   |rd = rs + rt|
+|addu       |R   |rd = rs + rt|
+|and        |R   |rd = rs & rt|
+|or         |R   |rd = rs \| rt|
+|slt        |R   |rd = rs < rt|
+|sltu       |R   |rd = rs < rt|
+|sub        |R   |rd = rs - rt|
+|subu       |R   |rd = rs - rt|
+|xor        |R   |rd = rs ^ rt|
+|sll        |R   |rd = rt << shamt|
+|sra        |R   |rd = rt >> shamt|
+|srl        |R   |rd = rt >> shamt|
+|div        |R   |hi = rs % rt lo = rs / rt|
+|divu       |R   |hi = rs % rt lo = rs / rt|
+|mult       |R   |hi, lo = rs * rt|
+|multu      |R   |hi, lo = rs * rt|
+|MFHI       |R   |rd = hi|
+|MFLO       |R   |rd = lo|
+|MTHI       |R   |rs = hi|
+|MTLO       |R   |rs = lo|
+|jr         |R   |pc = addr, pc = $ra|
+|jalr       |R   |rd = pc, pc = addr|
+|syscall    |R   |System Call|
+|jal        |J   |$ra = pc, pc = addr|
+|j          |J   |pc = addr|
+|beq        |I   | pc = (rs == rt) ? imm + pc + 4 : pc|
+|bne        |I   | pc = (rs != rt) ? imm + pc + 4 : pc|
+|addi       |I   |rt = rs + imm|
+|addiu      |I   |rt = rs + imm|
+|andi       |I   |rt = rs & imm|
+|ori        |I   |rt = rs \| imm|
+|xori       |I   |rt = rs ^ imm|
+|slti       |R   |rt = rs < imm|
+|sltiu      |R   |rt = rs < imm|
+|lui        |I   |rt = rs << 16|
+|lw         |I   |rs = imm(rt)|
+|sw         |I   |imm(rt) = rs|
+
+## Syscalls
+
+|Syscall|Action|
+|-------|------|
+|1      |Print integer in $a0|
+|2      |Not Implemented Yet|
+|3      |Not Implemented Yet|
+|4      |Print Null Terminated String, address in $a0|
+|5      |Read integer into $v0|
+|6      |Not Implemented Yet|
+|7      |Not Implemented Yet|
+|8      |Read string of length $a0 into memory at $a1|
+|9      |Not Implemented Yet|
+|10     |Exit with Status code 0|
+|11     |Print Character in $a0|
+|12     |Read Character into $v0|
+|13     |Not Implemented Yet|
+|14     |Not Implemented Yet|
+|15     |Not Implemented Yet|
+|16     |Not Implemented Yet|
+|17     |Exit with Status Code in $0|
+
diff --git a/binwrite.c b/binwrite.c
new file mode 100644
index 0000000..e70edbc
--- /dev/null
+++ b/binwrite.c
@@ -0,0 +1,21 @@
+#include <stdio.h>
+#include <stdint.h>
+
+int main(void) {
+	uint32_t insts[] = {
+		0x2008000a,			// addi $t0, $zero, 10
+		0x2009000b,			// addi $t1, $zero, 11
+		0x01285020,			// add  $t2, $t1, $t0
+		0x20020001,			// addi $v0, $zero, 1
+		0x000a2020,			// add $a0, $zero, $t2
+		0x0000000C,			// syscall
+		0x2002000a,			// addi $v0, $zero, 10
+		0x0000000C,			// syscall
+	};
+	FILE *fp = fopen("test.bin", "w");
+	for (size_t i = 0; i < sizeof(insts) / sizeof(insts[0]); i++) {
+		fwrite(insts + i, 1, 4, fp);
+	}
+	fclose(fp);
+	return 0;
+}
diff --git a/makefile b/makefile
new file mode 100644
index 0000000..e5c8228
--- /dev/null
+++ b/makefile
@@ -0,0 +1,13 @@
+CC=gcc
+CFLAGS=-Wall -Werror -pedantic --std=c17
+OBJS=mips.o
+TARGET=mips
+
+%.o: %.c
+	$(CC) $(CFLAGS) -c $@ $^
+
+all: $(TARGET)
+
+mips: $(OBJS)
+	$(CC) $(CFLAGS) -o $@ $^
+
diff --git a/mips b/mips
new file mode 100755
index 0000000..3a7a0a9
--- /dev/null
+++ b/mips
diff --git a/mips.c b/mips.c
new file mode 100644
index 0000000..dcda5f7
--- /dev/null
+++ b/mips.c
@@ -0,0 +1,315 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include <string.h>
+#include <arpa/inet.h>
+
+#define MEM_SIZE	36
+#define RA			31
+#define V0			2
+#define V1			3
+#define A0			4
+#define A1			5
+#define A2			6
+#define A3			7
+#define WORD_SIZE	4
+
+typedef struct {
+	unsigned int op: 6;
+	unsigned int rs: 5;
+	unsigned int rt: 5;
+	unsigned int rd: 5;
+	unsigned int shamt: 5;
+	unsigned int func: 6;
+} rtype_t;
+
+typedef struct {
+	unsigned int op: 6;
+	unsigned int rs: 5;
+	unsigned int rt: 5;
+	unsigned int imm: 16;
+} itype_t;
+
+typedef struct {
+	unsigned int op: 6;
+	unsigned int addr: 26;
+} jtype_t;
+
+typedef enum { NOP, RTYPE, ITYPE, JTYPE } type_t;
+
+typedef struct {
+	type_t type;
+	union {
+		uint32_t value;
+		rtype_t r;
+		jtype_t j;
+		itype_t i;
+	};
+} inst_t;
+
+uint8_t memory[MEM_SIZE] = {0};
+uint32_t pc = 0, hi = 0, lo = 0;
+uint32_t regFile[32] = {0};
+
+/* InstFetch: Fetch the next instruction from memory into the given
+ * instruction */
+void InstFetch(inst_t *inst) {
+	uint32_t value = 0;
+	memcpy(&value, memory + pc, WORD_SIZE);
+	switch ((value & 0xFC000000) >> 24) {
+		case 0:
+			inst->type = RTYPE;
+			inst->r.op = (value & 0xFC000000) >> 26;
+			inst->r.rs = (value & 0x03E00000) >> 21;
+			inst->r.rt = (value & 0x001F0000) >> 16;
+			inst->r.rd = (value & 0x0000F800) >> 11;
+			inst->r.shamt = (value & 0x000007C0) >> 6;
+			inst->r.func = value & 0x0000002F;
+			break;
+		case 2:
+		case 3:
+			inst->type = JTYPE;
+			inst->j.op = (value & 0xFC000000) >> 26;
+			inst->j.addr = value & 0X03FFFFFF;
+			break;
+		default:
+			inst->type = ITYPE;
+			inst->i.op = (value & 0xFC000000) >> 26;
+			inst->i.rs = (value & 0x03E00000) >> 21;
+			inst->i.rt = (value & 0x001F0000) >> 16;
+			inst->i.imm = value & 0x0000FFFF;
+			break;
+	}
+	if (inst->value == 0) {
+		inst->type = NOP;
+	}
+	pc += WORD_SIZE;
+}
+
+void Syscall(void) {
+	char c, *s;
+	switch (regFile[V0]) {
+		case 1:	// print integer
+			printf("%d", regFile[A0]);
+			break;
+		case 2:	// print float
+			break;
+		case 3:	// print double
+			break;
+		case 4:	// print string
+			printf("%s", memory + regFile[A0]);
+			break;
+		case 5:	// read integer
+			scanf("%d", (int *)regFile + V0);
+			break;
+		case 6:	// read float
+			break;
+		case 7:	// read double
+			break;
+		case 8:	// read string
+			s = (char *)calloc(regFile[A0], sizeof(char));
+			fgets(s, regFile[A0], stdin);
+			memcpy(memory + regFile[A1], s, regFile[A0]);
+			free(s);
+			break;
+		case 9:	// sbrk
+			break;
+		case 10:	//exit
+			exit(0);
+		case 11:	// print char
+			printf("%c", regFile[A0]);
+			break;
+		case 12:	// read char
+			c = 0;
+			scanf("%c", &c);
+			regFile[V0] = c;
+			break;
+		case 13:	// open file
+			break;
+		case 14:	// read from file
+			break;
+		case 15:	// write to file
+			break;
+		case 16:	// close file
+			break;
+		case 17:	// exit2
+			exit(regFile[A0]);
+	}
+}
+
+/* ExecRtype: Execute a given R-Type instruction */
+void ExecRtype(const inst_t inst) {
+	rtype_t r = inst.r;
+	uint32_t a = regFile[r.rs], b = regFile[r.rt];
+	uint64_t mult = 0;
+	switch (r.func) {
+		case 32: // add
+			regFile[r.rd] = (signed)a + (signed)b;
+			break;
+		case 33: // addu
+			regFile[r.rd] = a + b;
+			break;
+		case 36: // and
+			regFile[r.rd] = a & b;
+			break;
+		case 37: // or
+			regFile[r.rd] = a | b;
+			break;
+		case 42: // slt
+			regFile[r.rd] = (signed)a < (signed)b;
+			break;
+		case 43: // sltu
+			regFile[r.rd] = a < b;
+			break;
+		case 34: // sub
+			regFile[r.rd] = (signed)a - (signed)b;
+			break;
+		case 35: // subu
+			regFile[r.rd] = a - b;
+			break;
+		case 38: // xor
+			regFile[r.rd] = a ^ b;
+			break;
+		case 0: // sll
+			regFile[r.rd] = b << r.shamt;
+			break;
+		case 3: // sra
+			regFile[r.rd] = (signed)b >> r.shamt;
+			break;
+		case 2: // srl
+			regFile[r.rd] = b >> r.shamt;
+			break;
+		case 26: // div
+			hi = (signed)a % (signed)b;
+			lo = (signed)a / (signed)b;
+			break;
+		case 27: // divu
+			hi = a % b;
+			lo = a / b;
+			break;
+		case 24: // mult
+			mult = (signed)a * (signed)b;
+			hi = (0xFFFFFFFF00000000 & mult) >> 32;
+			lo = 0x00000000FFFFFFFF & mult;
+			break;
+		case 25: // multu
+			mult = a * b;
+			hi = (0xFFFFFFFF00000000 & mult) >> 32;
+			lo = 0x00000000FFFFFFFF & mult;
+			break;
+		case 16: // MFHI
+			regFile[r.rd] = hi;
+			break;
+		case 18: // MFLO
+			regFile[r.rd] = lo;
+			break;
+		case 17: // MTHI
+			hi = regFile[r.rs];
+			break;
+		case 19: // MTLO
+			lo = regFile[r.rs];
+			break;
+		case 8: // jr
+			pc = a;
+			break;
+		case 9: // jalr
+			regFile[r.rd] = pc + 4;
+			pc = a;
+			break;
+		case 12: // syscall
+			Syscall();
+			break;
+	}
+}
+
+/* InstExec: Execute a given instruction */
+void InstExec(const inst_t inst) {
+	if (inst.type == NOP) {
+		return;
+	}
+	switch (inst.j.op) {
+		case 0: // R-type instruction
+			ExecRtype(inst);
+			break;
+		case 3: // jal
+			regFile[RA] = pc + 4;
+			/* intentional fall through */
+		case 2: // j
+			pc = (0xF0000000 & pc ) | inst.j.addr;
+			break;
+		case 4: // beq
+			pc = (regFile[inst.i.rs] == regFile[inst.i.rt]) ? pc + 4 +
+				inst.i.imm : pc;
+			break;
+		case 5: // bne
+			pc = (regFile[inst.i.rs] != regFile[inst.i.rt]) ? pc + 4 +
+				inst.i.imm : pc;
+			break;
+		case 8: // addi
+			regFile[inst.i.rt] = (signed)inst.i.rs + (signed)inst.i.imm;
+			break;
+		case 9: // addiu
+			regFile[inst.i.rt] = inst.i.rs + inst.i.imm;
+			break;
+		case 12: // andi
+			regFile[inst.i.rt] = inst.i.rs & inst.i.imm;
+			break;
+		case 13: // ori
+			regFile[inst.i.rt] = inst.i.rs | inst.i.imm;
+			break;
+		case 14: // xori
+			regFile[inst.i.rt] = inst.i.rs ^ inst.i.imm;
+			break;
+		case 10: // slti
+			regFile[inst.i.rt] = (signed)inst.i.rs < (signed)inst.i.imm;
+			break;
+		case 11: // sltiu
+			regFile[inst.i.rt] = inst.i.rs < inst.i.imm;
+			break;
+		case 15: // lui
+			regFile[inst.i.rt] = inst.i.imm << 16;
+			break;
+		case 35: // lw
+			memcpy(regFile + inst.i.rs, memory + inst.i.rt + inst.i.imm,
+					WORD_SIZE);
+			break;
+		case 43: // sw
+			memcpy(memory + inst.i.rt + inst.i.imm, regFile + inst.i.rs,
+					WORD_SIZE);
+			break;
+	}
+}
+
+void CycleCpu(void) {
+	inst_t instFetch, instExec;
+	memset(&instFetch, 0, sizeof(inst_t));
+	memset(&instExec, 0, sizeof(inst_t));
+	while (pc < MEM_SIZE) {
+		InstFetch(&instFetch);
+		InstExec(instExec);
+		instExec = instFetch;
+	}
+}
+
+int LoadBinary(const char * const path) {
+	FILE *fp = fopen(path, "r");
+	if (fp == NULL) {
+		perror("LoadBinary");
+		return -1;
+	}
+	int8_t byte = 0;
+	size_t i = 0;
+	while ((byte = fgetc(fp)) != EOF && i < MEM_SIZE) {
+		memory[i++] = byte;
+	}
+	fclose(fp);
+	return 0;
+}
+
+int main(int argc, char *argv[]) {
+	if (LoadBinary(*++argv) == -1) {
+		return -1;
+	}
+	CycleCpu();
+}
+
diff --git a/mips.o b/mips.o
new file mode 100644
index 0000000..1a23fe9
--- /dev/null
+++ b/mips.o
diff --git a/test.bin b/test.bin
new file mode 100644
index 0000000..cb24090
--- /dev/null
+++ b/test.bin