refactoring

1 files changed, 20 insertions, 0 deletions

diff --git a/src/immediate_extend.v b/src/immediate_extend.v
new file mode 100644
index 0000000..749cf2b
--- /dev/null
+++ b/src/immediate_extend.v
@@ -0,0 +1,20 @@
+module immediate_extend (
+  input [31:0] instr,
+  input [2:0] imm_src,
+  output reg [31:0] imm
+);
+
+
+always @ (*) begin
+  case (imm_src)
+    3'b010:  imm <= { {21{instr[31]}}, instr[30:20] };                                // I
+    3'b011:  imm <= { {21{instr[31]}}, instr[30:25], instr[11:7] };                   // S
+    3'b100:  imm <= { {20{instr[31]}}, instr[7], instr[30:25], instr[11:8], 1'b0 };   // B
+    3'b101:  imm <= { instr[31:12], 12'b0 };                                          // U
+    3'b110:  imm <= { {12{instr[31]}}, instr[19:12], instr[20], instr[30:21], 1'b0 }; // J
+    default: imm <= 32'b0;                                                            // Unknown
+  endcase
+end
+
+
+endmodule