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https://github.com/pnx/m16vm
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50 lines
1.4 KiB
C
50 lines
1.4 KiB
C
/* instr_encode.c
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*
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* Copyright (C) 2018 Henrik Hautakoski <henrik@fiktivkod.org>
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*
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* This program 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 2 of the License, or
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* (at your option) any later version.
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*
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* This program 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 this program; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
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* MA 02110-1301, USA.
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*/
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#include <stdio.h>
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#include <string.h>
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#include "instr_encode.h"
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void instr_encode(struct instr* instr, uint16_t *out) {
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uint8_t *p = (uint8_t *) out;
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*out = 0;
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*p = instr->opcode << 4;
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if (instr->opcode == OP_NOOP) {
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// Do nothing.
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} else if (instr->opcode == OP_JMP) {
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*p |= (instr->j.addr >> 8);
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*(p+1) = instr->j.addr;
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} else {
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*p |= instr->r.rs;
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// I-Type
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if (instr->opcode == OP_MOVL || instr->opcode == OP_MOVH
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|| instr->opcode == OP_JR || instr->opcode == OP_INT) {
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*(p+1) = instr->i.imm;
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}
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// R/RI-Type
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else {
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*(p+1) = (instr->r.r0 << 4) | instr->r.r1;
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}
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}
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}
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