mirror of
https://github.com/Gehstock/Mist_FPGA.git
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69 lines
2.7 KiB
Plaintext
69 lines
2.7 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 0xae;
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jmp scasb, ra_sel DI;
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.auto_address;
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scasb:
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ra_sel DI, a_sel RA, alu_op SELA, mar_wr_sel Q, mar_write, rb_cl,
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jmp_if_not_rep scasb_no_rep;
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scasb_rep_loop:
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ra_sel CX, jmp_rb_zero scasb_done;
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ra_sel DI, a_sel RA, b_sel IMMEDIATE, immediate 0x1, alu_op SUB,
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rd_sel_source MICROCODE_RD_SEL, rd_sel CX, segment ES, segment_force;
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scasb_no_rep:
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width W8, segment ES, segment_force, mem_read, ra_sel AL,
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a_sel RA, alu_op SELA, tmp_wr_en;
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width W8, a_sel MDR, b_sel TEMP, alu_op SUBREV,
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update_flags OF SF ZF CF PF AF, jmp_if_not_rep scasb_done_no_rep;
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a_sel MAR, b_sel IMMEDIATE, immediate 0x1, alu_op NEXT,
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rd_sel_source MICROCODE_RD_SEL, rd_sel DI, mar_write, mar_wr_sel Q,
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rb_cl, ext_int_yield, jmp_if_rep_not_complete scasb_rep_loop,
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segment ES, segment_force;
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scasb_done:
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next_instruction;
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scasb_done_no_rep:
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a_sel MAR, b_sel IMMEDIATE, immediate 0x1, alu_op NEXT,
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rd_sel_source MICROCODE_RD_SEL, rd_sel DI, next_instruction;
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.at 0xaf;
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jmp scasw, ra_sel DI;
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.auto_address;
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scasw:
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ra_sel DI, a_sel RA, alu_op SELA, mar_wr_sel Q, mar_write,
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rb_cl, jmp_if_not_rep scasw_no_rep;
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scasw_rep_loop:
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ra_sel CX, jmp_rb_zero scasw_done;
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ra_sel DI, a_sel RA, b_sel IMMEDIATE, immediate 0x1, alu_op SUB,
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rd_sel_source MICROCODE_RD_SEL, rd_sel CX, segment ES, segment_force;
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scasw_no_rep:
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segment ES, segment_force, mem_read, ra_sel AX, a_sel RA, alu_op SELA,
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tmp_wr_en;
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a_sel MDR, b_sel TEMP, alu_op SUBREV, update_flags OF SF ZF CF PF AF,
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jmp_if_not_rep scasw_done_no_rep;
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a_sel MAR, b_sel IMMEDIATE, immediate 0x2, alu_op NEXT,
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rd_sel_source MICROCODE_RD_SEL, rd_sel DI, mar_write, mar_wr_sel Q,
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rb_cl, ext_int_yield, jmp_if_rep_not_complete scasw_rep_loop,
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segment ES, segment_force;
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scasw_done:
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next_instruction;
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scasw_done_no_rep:
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a_sel MAR, b_sel IMMEDIATE, immediate 0x2, alu_op NEXT,
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rd_sel_source MICROCODE_RD_SEL, rd_sel DI, next_instruction;
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