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https://github.com/pnx/m16vm
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56 lines
1.7 KiB
C
56 lines
1.7 KiB
C
/* codegen.c
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*
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* Copyright (C) 2018-2019 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 "codegen.h"
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void codegen_emit(struct ast_instr* instr, symtab_t* symbols, uint8_t* out) {
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out[0] = instr->opcode << 4;
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if (instr->n_operands < 1)
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// No operands, return
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return;
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// J-Type
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if (instr->operands[0].type == DATATYPE_STRING) {
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uint16_t addr;
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if (symtab_get(symbols, instr->operands[0].s, &addr) >= 0) {
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out[0] |= (addr >> 8);
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out[1] = addr;
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}
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}
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// R/RI or I
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else if (instr->operands[0].type == DATATYPE_REGISTER) {
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out[0] |= instr->operands[0].r & 0xF;
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// I
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if (instr->operands[1].type == DATATYPE_NUMBER) {
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out[1] = instr->operands[1].n;
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}
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// R/RI-Type
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else if (instr->operands[1].type == DATATYPE_REGISTER &&
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(instr->operands[2].type == DATATYPE_REGISTER || instr->operands[2].type == DATATYPE_NUMBER)) {
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out[1] = (instr->operands[1].r << 4) | (instr->operands[2].r & 0xF);
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}
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}
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}
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