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// immediate extend:
// Extracts immediate value from various instruction formats.
module immediate_extend (
input [31:0] instr,
input [2:0] imm_src,
output reg [31:0] imm
);
`include "include/consts.vh"
always @ (*) begin
case (imm_src)
INSTR_FORMAT_I: imm = { {21{instr[31]}}, instr[30:20] }; // I
INSTR_FORMAT_S: imm = { {21{instr[31]}}, instr[30:25], instr[11:7] }; // S
INSTR_FORMAT_B: imm = { {20{instr[31]}}, instr[7], instr[30:25], instr[11:8], 1'b0 }; // B
INSTR_FORMAT_U: imm = { instr[31:12], 12'b0 }; // U
INSTR_FORMAT_J: imm = { {12{instr[31]}}, instr[19:12], instr[20], instr[30:21], 1'b0 }; // J
default: imm = 32'b0; // Unknown
endcase
end
endmodule
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