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https://github.com/Gehstock/Mist_FPGA.git
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67 lines
2.5 KiB
Plaintext
67 lines
2.5 KiB
Plaintext
// Copyright Jamie Iles, 2017
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//
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// This file is part of s80x86.
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//
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// s80x86 is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// s80x86 is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with s80x86. If not, see <http://www.gnu.org/licenses/>.
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.at 0xc8;
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b_sel IMMEDIATE, alu_op SELB, tmp_wr_en, ra_sel SP, jmp enter;
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.auto_address;
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enter:
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// Push BP
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a_sel RA, b_sel IMMEDIATE, immediate 0x2, alu_op SUB, mar_write,
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mar_wr_sel Q, ra_sel BP, rd_sel_source MICROCODE_RD_SEL, rd_sel SP;
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a_sel RA, alu_op SELA, mdr_write, segment_force, segment SS;
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segment_force, segment SS, mem_write, ra_sel SP,
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jmp_loop_done enter_out_nonest;
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// Push frame temp
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a_sel RA, b_sel IMMEDIATE2, alu_op ENTER_FRAME_TEMP_ADDR, mar_write,
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mar_wr_sel Q, ra_sel SP;
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a_sel RA, alu_op SELA, mdr_write, segment_force, segment SS;
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segment_force, segment SS, mem_write;
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enter_loop:
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jmp_loop_done enter_out, ra_sel BP;
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// BP := BP - 2
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a_sel RA, b_sel IMMEDIATE, immediate 0x2, alu_op SUB, rd_sel BP,
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rd_sel_source MICROCODE_RD_SEL, segment_force, segment SS,
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mar_write, mar_wr_sel Q;
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// push [BP]
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segment_force, segment SS, mem_read, ra_sel SP;
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a_sel RA, b_sel IMMEDIATE, immediate 0x2, alu_op SUB, rd_sel SP,
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rd_sel_source MICROCODE_RD_SEL, segment_force, segment SS,
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mar_write, mar_wr_sel Q;
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segment_force, segment SS, mem_write;
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jmp enter_loop;
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enter_out:
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// Reload frame_temp
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ra_sel SP;
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a_sel RA, b_sel IMMEDIATE, immediate 0x2, alu_op SUB, rd_sel SP,
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rd_sel_source MICROCODE_RD_SEL, segment_force, segment SS,
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mar_write, mar_wr_sel Q;
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segment_force, segment SS, mem_read, ra_sel SP;
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a_sel MDR, alu_op SELA, rd_sel BP, rd_sel_source MICROCODE_RD_SEL,
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ra_sel SP;
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// SP := SP - size
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a_sel RA, b_sel TEMP, alu_op SUB, rd_sel SP, rd_sel_source MICROCODE_RD_SEL,
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next_instruction;
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enter_out_nonest:
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a_sel RA, alu_op SELA, rd_sel BP, rd_sel_source MICROCODE_RD_SEL,
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ra_sel SP;
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a_sel RA, b_sel TEMP, alu_op SUB, rd_sel SP, rd_sel_source MICROCODE_RD_SEL,
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next_instruction;
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