Change exception handling, more instructions implemented

1 files changed, 73 insertions, 8 deletions

diff --git a/nios2.h b/nios2.h
index a24ab1d..f777369 100644
--- a/nios2.h
+++ b/nios2.h
@@ -19,6 +19,8 @@
 /* there are really 32, but 16-31 are reserved for future use */
 #define NIOS2_CTRL_REG_COUNT	16
 
+struct tlb_entry;
+
 struct nios2 {
 	/* General-Purpose Registers */
 	uint32_t gp_regs[NIOS2_GP_REG_COUNT];
@@ -27,7 +29,9 @@ struct nios2 {
 	/* Program counter */
 	uint32_t pc;
 	/* User or Supervisor mode */
-	int mode;
+	unsigned int mode;
+	/* Exception cause */
+	unsigned int exception_cause;
 
 	/* Configurable processor features */
 	bool has_mul;	/* mul, muli */
@@ -36,11 +40,21 @@ struct nios2 {
 
 	bool has_mmu;	/* Memory Management Unit */
 
+	/*
+	struct tlb_entry tlb[TLB_NUM_LINES][TLB_NUM_WAYS];
+	*/
+
 	struct memory *mem;
 	/* Exception handler address */
 	uint32_t exception_handler_addr;
 };
 
+/* processor modes */
+enum {
+	NIOS2_SUPERVISOR_MODE,
+	NIOS2_USER_MODE,	/* only used with MMU */
+};
+
 /* Aliases for general-purpose registers */
 enum {
 	zero = 0,
@@ -76,23 +90,74 @@ enum {
 };
 
 /* status register fields */
-#define NIOS2_STATUS_PIE	0
-#define NIOS2_STATUS_U		1
-#define NIOS2_STATUS_EH		2
+#define NIOS2_STATUS_PIE_MASK		0x00000001
+#define NIOS2_STATUS_U_MASK		0x00000002
+#define NIOS2_STATUS_EH_MASK		0x00000004
+
+/* exception register fields */
+#define NIOS2_EXCEPTION_CAUSE_MASK	0x0000007C
+#define NIOS2_EXCEPTION_CAUSE_OFF	2
 
 /* exception causes */
 #define NIOS2_EX_RESET			0
 #define NIOS2_EX_PROC_ONLY_RESET	1
 #define NIOS2_EX_IRQ			2
+#define NIOS2_EX_TRAP			3
 #define NIOS2_EX_UNIMPLEMENTED		4
 #define NIOS2_EX_DIV_ERR		8
 #define NIOS2_EX_SUPERVISOR_ONLY_I	9
 #define NIOS2_EX_SUPERVISOR_ONLY_D	11
 #define NIOS2_EX_FAST_TLB_MISS		12
 
-enum {
-	NIOS2_SUPERVISOR_MODE,
-	NIOS2_USER_MODE,
+#define NIOS2_EX_NONE			255
+
+/* pteaddr register fields */
+#define NIOS2_PTEADDR_VPN_SHIFT		2
+#define NIOS2_PTEADDR_VPN_MASK		0x007FFFFC
+#define NIOS2_PTEADDR_PTBASE_SHIFT	22
+#define NIOS2_PTEADDR_PTBASE_MASK	0xFFC00000
+
+/* tlbacc register fields */
+#define NIOS2_TLBACC_PFN_MASK	0x000FFFFF
+#define NIOS2_TLBACC_G_MASK	0x00100000
+#define NIOS2_TLBACC_X_MASK	0x00200000
+#define NIOS2_TLBACC_W_MASK	0x00400000
+#define NIOS2_TLBACC_R_MASK	0x00800000
+#define NIOS2_TLBACC_C_MASK	0x01000000
+
+/* tlbmisc register fields */
+#define NIOS2_TLBMISC_D_MASK	0x00000001
+#define NIOS2_TLBMISC_PERM_MASK	0x00000002
+#define NIOS2_TLBMISC_BAD_MASK	0x00000004
+#define NIOS2_TLBMISC_DBL_MASK	0x00000008
+#define NIOS2_TLBMISC_PID_MASK	0x0007FFF0
+#define NIOS2_TLBMISC_PID_OFF	4
+#define NIOS2_TLBMISC_WE_MASK	0x00040000
+#define NIOS2_TLBMISC_RD_MASK	0x00080000
+#define NIOS2_TLBMISC_WAY_MASK	0x0007FFF0
+#define NIOS2_TLBMISC_WAY_OFF	20
+
+/* MMU-specific stuff */
+
+#define TLB_NUM_ENTRIES	256
+#define TLB_NUM_WAYS	16
+#define TLB_NUM_LINES	(TLB_NUM_ENTRIES / TLB_NUM_WAYS)
+
+struct tlb_entry {
+	/* TLB Tag Portion */
+	uint32_t vpn;
+	uint16_t pid;
+	uint8_t g;
+
+	/* TLB Data Portion Contents */
+	uint32_t pfn;
+	uint8_t c;
+	uint8_t r;
+	uint8_t w;
+	uint8_t x;
+
+	/* TLB Data */
+	uint32_t buffer;
 };
 
 extern void nios2_cpu_reset(struct nios2 *cpu);
@@ -101,7 +166,7 @@ extern void nios2_simulate(struct nios2 *cpu);
 extern void nios2_cpu_inc_pc(struct nios2 *cpu);
 extern bool nios2_in_user_mode(struct nios2 *cpu);
 extern bool nios2_in_supervisor_mode(struct nios2 *cpu);
-extern void nios2_exception(struct nios2 *cpu, uint8_t cause);
+extern void nios2_handle_exception(struct nios2 *cpu);
 extern uint32_t nios2_fetch_instr(struct nios2 *cpu);
 extern int nios2_execute_instr(struct nios2 *cpu, uint32_t instr);