1 files changed, 32 insertions, 0 deletions
diff --git a/rtl/core/regs/map.sv b/rtl/core/regs/map.sv
new file mode 100644
index 0000000..b4da988
--- /dev/null
+++ b/rtl/core/regs/map.sv
@@ -0,0 +1,32 @@
+`include "core/isa.sv"
+`include "core/psr.sv"
+`include "core/uarch.sv"
+
+module core_reg_map
+(
+	input  reg_num   r,
+	input  psr_mode  mode,
+	output logic     is_pc,
+	output reg_index index
+);
+
+	reg_index usr;
+	assign usr = {1'b0, r};
+
+	always_comb begin
+		index = 5'bxxxxx;
+		is_pc = r == `R15;
+
+		if(~is_pc)
+			unique case(mode)
+				`MODE_USR, `MODE_SYS: index = usr;
+				`MODE_FIQ: index = r >=  8 ? usr +  7 : usr;
+				`MODE_IRQ: index = r >= 13 ? usr +  9 : usr;
+				`MODE_UND: index = r >= 13 ? usr + 11 : usr;
+				`MODE_ABT: index = r >= 13 ? usr + 13 : usr;
+				`MODE_SVC: index = r >= 13 ? usr + 15 : usr;
+				default: ;
+			endcase
+	end
+
+endmodule