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view lwasm/insn_rel.c @ 129:5706712f8a20
Allow [>...] for extended indirect
author | lost@l-w.ca |
---|---|
date | Thu, 11 Aug 2011 22:25:29 -0600 |
parents | 2be2649841f8 |
children | 6f2e18f1fe67 |
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/* insn_rel.c Copyright © 2009 William Astle This file is part of LWASM. LWASM is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see <http://www.gnu.org/licenses/>. */ /* for handling relative mode instructions */ #include <ctype.h> #include <stdlib.h> #include <stdio.h> #include <lw_expr.h> #include "lwasm.h" #include "instab.h" /* For generic relative, the first "opcode" is the natural opcode for the mneumonic. The second "opcode" is the natural size of the relative offset. These will be used when pragma autobranchlength is NOT in effect. The third "opcode" is the short (8 bit) version of the branch. The final one is the long (16 bit) version of the branch. These will be used when pragma autobranchlength is in effect. When autobranchlength is in effect, the branch target can be prefixed with either < or > to force a short or long branch. Note that in this mode, a > or < on its own still specifies a branch point. */ PARSEFUNC(insn_parse_relgen) { lw_expr_t t, e1, e2; l -> lint = -1; if (CURPRAGMA(l, PRAGMA_AUTOBRANCHLENGTH) == 0) { l -> lint = instab[l -> insn].ops[1]; } else { if (**p == '>' && (((*p)[1]) && !isspace((*p)[1]))) { (*p)++; l -> lint = 16; } else if (**p == '<' && (((*p)[1]) && !isspace((*p)[1]))) { (*p)++; l -> lint = 8; } } /* forced sizes handled */ // sometimes there is a "#", ignore if there if (**p == '#') (*p)++; t = lwasm_parse_expr(as, p); if (!t) { lwasm_register_error(as, l, "Bad operand"); return; } // if we know the length of the instruction, set it now if (l -> lint == 8) { l -> len = OPLEN(instab[l -> insn].ops[2]) + 1; } else if (l -> lint == 16) { l -> len = OPLEN(instab[l -> insn].ops[3]) + 2; } // the offset calculation here depends on the length of this line! // how to calculate requirements? // this is the same problem faced by ,pcr indexing e2 = lw_expr_build(lw_expr_type_special, lwasm_expr_linelen, l); e1 = lw_expr_build(lw_expr_type_oper, lw_expr_oper_minus, t, e2); lw_expr_destroy(e2); e2 = lw_expr_build(lw_expr_type_oper, lw_expr_oper_minus, e1, l -> addr); lw_expr_destroy(e1); lwasm_save_expr(l, 0, e2); lw_expr_destroy(t); if (l -> len == -1) { e1 = lw_expr_copy(e2); l -> len = OPLEN(instab[l -> insn].ops[2]) + 1; lwasm_reduce_expr(as, e1); l -> len = -1; if (lw_expr_istype(e1, lw_expr_type_int)) { int v; v = lw_expr_intval(e1); if (v >= -128 && v <= 127) { l -> lint = 8; l -> len = OPLEN(instab[l -> insn].ops[2]) + 1; } else { l -> lint = 16; l -> len = OPLEN(instab[l -> insn].ops[3]) + 2; } } lw_expr_destroy(e1); } } RESOLVEFUNC(insn_resolve_relgen) { lw_expr_t e, e2; int offs; if (l -> lint == -1) { e = lwasm_fetch_expr(l, 0); if (!lw_expr_istype(e, lw_expr_type_int)) { // temporarily set the instruction length to see if we get a // constant for our expression; if so, we can select an instruction // size e2 = lw_expr_copy(e); // size of 8-bit opcode + 8 bit offset l -> len = OPLEN(instab[l -> insn].ops[2]) + 1; lwasm_reduce_expr(as, e2); l -> len = -1; if (lw_expr_istype(e2, lw_expr_type_int)) { // it reduced to an integer; is it in 8 bit range? offs = lw_expr_intval(e2); if (offs >= -128 && offs <= 127) { // fits in 8 bits l -> len = OPLEN(instab[l -> insn].ops[2]) + 1; l -> lint = 8; } else { // requires 16 bits l -> len = OPLEN(instab[l -> insn].ops[3]) + 2; l -> lint = 16; } } lw_expr_destroy(e2); } if (lw_expr_istype(e, lw_expr_type_int)) { // it reduced to an integer; is it in 8 bit range? offs = lw_expr_intval(e); if (offs >= -128 && offs <= 127) { // fits in 8 bits l -> len = OPLEN(instab[l -> insn].ops[2]) + 1; l -> lint = 8; } else { // requires 16 bits l -> len = OPLEN(instab[l -> insn].ops[3]) + 2; l -> lint = 16; } } } if (!force) return; if (l -> len == -1) { l -> len = OPLEN(instab[l -> insn].ops[3]) + 2; l -> lint = 16; } } EMITFUNC(insn_emit_relgen) { lw_expr_t e; int offs; e = lwasm_fetch_expr(l, 0); if (l -> lint == 8) { if (!lw_expr_istype(e, lw_expr_type_int)) { lwasm_register_error(as, l, "Illegal non-constant expression"); return; } offs = lw_expr_intval(e); if (l -> lint == 8 && (offs < -128 || offs > 127)) { lwasm_register_error(as, l, "Byte overflow"); return; } lwasm_emitop(l, instab[l -> insn].ops[2]); lwasm_emit(l, offs); } else { lwasm_emitop(l, instab[l -> insn].ops[3]); lwasm_emitexpr(l, e, 2); } }