Implement breakpoints

3 files changed, 18 insertions, 2 deletions

diff --git a/rtl/core/decode/decode.sv b/rtl/core/decode/decode.sv
index f16db9a..6534897 100644
--- a/rtl/core/decode/decode.sv
+++ b/rtl/core/decode/decode.sv
@@ -29,6 +29,7 @@ module core_decode
 	assign dec_ctrl.mul = mul;
 	assign dec_ctrl.psr = psr;
 	assign dec_ctrl.ldst = ldst;
+	assign dec_ctrl.bkpt = bkpt;
 	assign dec_ctrl.branch = branch;
 	assign dec_ctrl.coproc = coproc;
 	assign dec_ctrl.execute = execute;
@@ -44,8 +45,8 @@ module core_decode
 	assign dec_psr.restore_spsr = restore_spsr;
 
 	logic execute, undefined, conditional, writeback, update_flags,
-	      restore_spsr, branch, ldst, mul, psr, coproc, psr_saved,
-	      psr_write, psr_wr_flags, psr_wr_control;
+	      restore_spsr, branch, ldst, mul, psr, coproc, bkpt,
+	      psr_saved, psr_write, psr_wr_flags, psr_wr_control;
 
 	core_decode_mux mux
 	(
diff --git a/rtl/core/decode/isa.sv b/rtl/core/decode/isa.sv
index 7c27f49..4c9f316 100644
--- a/rtl/core/decode/isa.sv
+++ b/rtl/core/decode/isa.sv
@@ -209,4 +209,8 @@
 
 `define FIELD_SWI_IMM [23:0]
 
+// GDB swbreak (a magic 'und')
+
+`define INSN_GDB_SWBREAK 28'h7ffdefe 
+
 `endif
diff --git a/rtl/core/decode/mux.sv b/rtl/core/decode/mux.sv
index 3f613a4..f05b711 100644
--- a/rtl/core/decode/mux.sv
+++ b/rtl/core/decode/mux.sv
@@ -57,6 +57,7 @@ module core_decode_mux
 	                     mul,
 	                     psr,
 	                     coproc,
+	                     bkpt,
 	                     psr_saved,
 	                     psr_write,
 	                     psr_wr_flags,
@@ -71,6 +72,7 @@ module core_decode_mux
 	always_comb begin
 		mul = 0;
 		ldst = 0;
+		bkpt = 0;
 		branch = 0;
 		coproc = 0;
 		execute = 1;
@@ -230,6 +232,14 @@ module core_decode_mux
 				writeback = 1;
 			end
 
+`ifdef VERILATOR
+			// No es parte de ARM del todo, es un hack para soportar gdb
+			`INSN_GDB_SWBREAK: begin
+				bkpt = 1;
+				dec_data.uses_rn = 0;
+			end
+`endif
+
 			default:
 				undefined = 1;
 		endcase
@@ -252,6 +262,7 @@ module core_decode_mux
 
 			mul = 1'bx;
 			psr = 1'bx;
+			bkpt = 1'bx;
 			ldst = 1'bx;
 			branch = 1'bx;
 			coproc = 1'bx;