rtl/core: implement ldrex/strex decode

8 files changed, 68 insertions, 6 deletions

diff --git a/rtl/core/decode/decode.sv b/rtl/core/decode/decode.sv
index b00e06f..219f975 100644
--- a/rtl/core/decode/decode.sv
+++ b/rtl/core/decode/decode.sv
@@ -127,6 +127,16 @@ module core_decode
 		.*
 	);
 
+	reg_num ldst_ex_snd_r;
+	ldst_decode ldst_exclusive;
+
+	core_decode_ldst_exclusive group_ldst_ex
+	(
+		.snd_r(ldst_ex_snd_r),
+		.decode(ldst_exclusive),
+		.*
+	);
+
 	ldst_decode ldst_addr;
 	data_decode data_ldst;
 
diff --git a/rtl/core/decode/isa.sv b/rtl/core/decode/isa.sv
index 2ad5b40..6784eca 100644
--- a/rtl/core/decode/isa.sv
+++ b/rtl/core/decode/isa.sv
@@ -162,7 +162,18 @@
 `define FIELD_LDST_MULT_RN   [19:16]
 `define FIELD_LDST_MULT_LIST [15:0]
 
-// Instrucciones atómicas de intercambio registro-memoria
+// Instrucciones para operaciones atómicas optimistas (monitor exclusivo)
+
+`define INSN_LDREX    28'b0001100_1_????_????_1111_1001_1111
+`define INSN_STREX    28'b0001100_0_????_????_1111_1001_????
+`define GROUP_LDST_EX `INSN_LDREX, `INSN_STREX
+
+`define FIELD_LDST_EX_LD   [20]
+`define FIELD_LDST_EX_RN   [19:16]
+`define FIELD_LDST_EX_RD   [15:12]
+`define FIELD_LDST_EX_R_OK [3:0]
+
+// Instrucciones atómicas de intercambio registro-memoria (deprecadas)
 
 `define INSN_SWP  28'b00010000_????_????_0000_1001_????
 `define INSN_SWPB 28'b00010100_????_????_0000_1001_????
diff --git a/rtl/core/decode/ldst/exclusive.sv b/rtl/core/decode/ldst/exclusive.sv
new file mode 100644
index 0000000..7942a04
--- /dev/null
+++ b/rtl/core/decode/ldst/exclusive.sv
@@ -0,0 +1,27 @@
+`include "core/decode/isa.sv"
+`include "core/uarch.sv"
+
+module core_decode_ldst_exclusive
+(
+	input  word        insn,
+
+	output ldst_decode decode,
+	output reg_num     snd_r
+);
+
+	assign snd_r = insn `FIELD_LDST_EX_R_OK;
+
+	assign decode.rn = insn `FIELD_LDST_EX_RN;
+	assign decode.rd = insn `FIELD_LDST_EX_RD;
+	assign decode.size = LDST_WORD;
+	assign decode.load = insn `FIELD_LDST_EX_LD;
+	assign decode.increment = 0;
+	assign decode.writeback = 0;
+	assign decode.exclusive = 1;
+	assign decode.sign_extend = 0;
+	assign decode.pre_indexed = 0;
+	assign decode.unprivileged = 0;
+	assign decode.user_regs = 0;
+	assign decode.regs = 16'b0;
+
+endmodule
diff --git a/rtl/core/decode/ldst/misc.sv b/rtl/core/decode/ldst/misc.sv
index 4e4a17e..72d648c 100644
--- a/rtl/core/decode/ldst/misc.sv
+++ b/rtl/core/decode/ldst/misc.sv
@@ -19,6 +19,7 @@ module core_decode_ldst_misc
 	assign decode.load = insn `FIELD_LDST_LD;
 	assign decode.increment = insn `FIELD_LDST_MISC_U;
 	assign decode.writeback = !p || w;
+	assign decode.exclusive = 0;
 	assign decode.sign_extend = insn `FIELD_LDST_MISC_S;
 	assign decode.pre_indexed = p;
 	assign decode.unprivileged = 0;
diff --git a/rtl/core/decode/ldst/multiple.sv b/rtl/core/decode/ldst/multiple.sv
index 0ecd674..c822ab0 100644
--- a/rtl/core/decode/ldst/multiple.sv
+++ b/rtl/core/decode/ldst/multiple.sv
@@ -18,6 +18,7 @@ module core_decode_ldst_multiple
 	assign decode.load = l;
 	assign decode.increment = insn `FIELD_LDST_MULT_U;
 	assign decode.writeback = insn `FIELD_LDST_MULT_W;
+	assign decode.exclusive = 0;
 	assign decode.sign_extend = 0;
 	assign decode.pre_indexed = insn `FIELD_LDST_MULT_P;
 	assign decode.unprivileged = 0;
diff --git a/rtl/core/decode/ldst/single.sv b/rtl/core/decode/ldst/single.sv
index 402c17b..af096a7 100644
--- a/rtl/core/decode/ldst/single.sv
+++ b/rtl/core/decode/ldst/single.sv
@@ -17,6 +17,7 @@ module core_decode_ldst_single
 	assign decode.load = insn `FIELD_LDST_LD;
 	assign decode.increment = insn `FIELD_LDST_SINGLE_U;
 	assign decode.writeback = !p || w;
+	assign decode.exclusive = 0;
 	assign decode.sign_extend = 0;
 	assign decode.pre_indexed = p;
 	assign decode.unprivileged = !p && w;
diff --git a/rtl/core/decode/mux.sv b/rtl/core/decode/mux.sv
index 297ad33..6f0451a 100644
--- a/rtl/core/decode/mux.sv
+++ b/rtl/core/decode/mux.sv
@@ -18,12 +18,14 @@ module core_decode_mux
 	                     data_is_imm,
 	                     data_shift_by_reg_if_reg,
 
-	input  ldst_decode   ldst_single,
-	                     ldst_misc,
+	input  ldst_decode   ldst_misc,
+	                     ldst_single,
 	                     ldst_multiple,
+	                     ldst_exclusive,
 	input  logic         ldst_single_is_imm,
 	                     ldst_misc_off_is_imm,
-	input  reg_num       ldst_misc_off_reg,
+	input  reg_num       ldst_ex_snd_r,
+	                     ldst_misc_off_reg,
 	input  logic[7:0]    ldst_misc_off_imm,
 	input  logic         ldst_mult_restore_spsr,
 	input  data_decode   data_ldst,
@@ -135,6 +137,14 @@ module core_decode_mux
 				update_flags = mul_update_flags;
 			end
 
+			`GROUP_LDST_EX: begin
+				dec_ldst = ldst_exclusive;
+				ldst_addr = ldst_exclusive;
+
+				dec_snd.r = ldst_ex_snd_r;
+				dec_snd.is_imm = ldst_exclusive.load;
+			end
+
 			`GROUP_LDST_MISC: begin
 				dec_ldst = ldst_misc;
 				ldst_addr = ldst_misc;
@@ -255,10 +265,10 @@ module core_decode_mux
 			// Codificación coincide con ldst
 			`GROUP_MUL: ;
 
-			`GROUP_LDST_SINGLE, `GROUP_LDST_MISC, `GROUP_LDST_MULT: begin
+			`GROUP_LDST_SINGLE, `GROUP_LDST_MISC, `GROUP_LDST_MULT, `GROUP_LDST_EX: begin
 				ldst = 1;
 				dec_data = data_ldst;
-				writeback = dec_ldst.writeback || dec_ldst.load;
+				writeback = dec_ldst.writeback || dec_ldst.load || dec_ldst.exclusive;
 			end
 
 			default: ;
diff --git a/rtl/core/uarch.sv b/rtl/core/uarch.sv
index 38b0130..a474274 100644
--- a/rtl/core/uarch.sv
+++ b/rtl/core/uarch.sv
@@ -150,6 +150,7 @@ typedef struct packed
 	logic       load,
 	            increment,
 	            writeback,
+	            exclusive,
 	            sign_extend,
 	            pre_indexed,
 	            unprivileged,