mirror of
https://github.com/Polprzewodnikowy/SummerCart64.git
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96 lines
3.0 KiB
Coq
96 lines
3.0 KiB
Coq
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`default_nettype none
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module serv_immdec
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#(parameter SHARED_RFADDR_IMM_REGS = 1)
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(
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input wire i_clk,
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//State
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input wire i_cnt_en,
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input wire i_cnt_done,
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//Control
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input wire [3:0] i_immdec_en,
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input wire i_csr_imm_en,
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input wire [3:0] i_ctrl,
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output wire [4:0] o_rd_addr,
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output wire [4:0] o_rs1_addr,
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output wire [4:0] o_rs2_addr,
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//Data
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output wire o_csr_imm,
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output wire o_imm,
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//External
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input wire i_wb_en,
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input wire [31:7] i_wb_rdt);
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reg imm31;
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reg [8:0] imm19_12_20;
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reg imm7;
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reg [5:0] imm30_25;
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reg [4:0] imm24_20;
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reg [4:0] imm11_7;
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assign o_csr_imm = imm19_12_20[4];
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wire signbit = imm31 & !i_csr_imm_en;
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generate
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if (SHARED_RFADDR_IMM_REGS) begin : gen_shared_imm_regs
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assign o_rs1_addr = imm19_12_20[8:4];
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assign o_rs2_addr = imm24_20;
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assign o_rd_addr = imm11_7;
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always @(posedge i_clk) begin
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if (i_wb_en) begin
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/* CSR immediates are always zero-extended, hence clear the signbit */
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imm31 <= i_wb_rdt[31];
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end
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if (i_wb_en | (i_cnt_en & i_immdec_en[1]))
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imm19_12_20 <= i_wb_en ? {i_wb_rdt[19:12],i_wb_rdt[20]} : {i_ctrl[3] ? signbit : imm24_20[0], imm19_12_20[8:1]};
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if (i_wb_en | (i_cnt_en))
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imm7 <= i_wb_en ? i_wb_rdt[7] : signbit;
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if (i_wb_en | (i_cnt_en & i_immdec_en[3]))
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imm30_25 <= i_wb_en ? i_wb_rdt[30:25] : {i_ctrl[2] ? imm7 : i_ctrl[1] ? signbit : imm19_12_20[0], imm30_25[5:1]};
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if (i_wb_en | (i_cnt_en & i_immdec_en[2]))
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imm24_20 <= i_wb_en ? i_wb_rdt[24:20] : {imm30_25[0], imm24_20[4:1]};
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if (i_wb_en | (i_cnt_en & i_immdec_en[0]))
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imm11_7 <= i_wb_en ? i_wb_rdt[11:7] : {imm30_25[0], imm11_7[4:1]};
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end
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end else begin : gen_separate_imm_regs
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reg [4:0] rd_addr;
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reg [4:0] rs1_addr;
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reg [4:0] rs2_addr;
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assign o_rd_addr = rd_addr;
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assign o_rs1_addr = rs1_addr;
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assign o_rs2_addr = rs2_addr;
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always @(posedge i_clk) begin
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if (i_wb_en) begin
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/* CSR immediates are always zero-extended, hence clear the signbit */
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imm31 <= i_wb_rdt[31];
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imm19_12_20 <= {i_wb_rdt[19:12],i_wb_rdt[20]};
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imm7 <= i_wb_rdt[7];
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imm30_25 <= i_wb_rdt[30:25];
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imm24_20 <= i_wb_rdt[24:20];
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imm11_7 <= i_wb_rdt[11:7];
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rd_addr <= i_wb_rdt[11:7];
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rs1_addr <= i_wb_rdt[19:15];
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rs2_addr <= i_wb_rdt[24:20];
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end
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if (i_cnt_en) begin
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imm19_12_20 <= {i_ctrl[3] ? signbit : imm24_20[0], imm19_12_20[8:1]};
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imm7 <= signbit;
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imm30_25 <= {i_ctrl[2] ? imm7 : i_ctrl[1] ? signbit : imm19_12_20[0], imm30_25[5:1]};
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imm24_20 <= {imm30_25[0], imm24_20[4:1]};
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imm11_7 <= {imm30_25[0], imm11_7[4:1]};
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end
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end
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end
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endgenerate
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assign o_imm = i_cnt_done ? signbit : i_ctrl[0] ? imm11_7[0] : imm24_20[0];
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endmodule
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