diff options
Diffstat (limited to 'gen_code.c')
| -rw-r--r-- | gen_code.c | 61 |
1 files changed, 61 insertions, 0 deletions
@@ -13,6 +13,7 @@ else yyerror("CAN'T POP");} #define REG_PUSH {if (reg_cnt < 13) reg_ptr--, reg_cnt++;\ else yyerror("CAN'T PUSH");} +#define GEN_EXPR(x) {gen_label(x); gen_expr(x);} char **reg_stack, **reg_ptr; int reg_cnt; @@ -45,9 +46,69 @@ ptree *t; } +/*Based on Dragon Book gen_code()*/ void gen_expr(t) ptree *t; { + if (!t) { + fprintf(stderr, "GEN_EXPR: NOT T\n"); + return; + } + + /*case 0 + * t is a left leaf*/ + if ((!t->r) && (!t->l) && t->label != 0) { + switch (t->type) { + case ID: + fprintf(stdout, "mov\t%s, %s\n",t->attr.nval->name, *reg_ptr); + break; + case INUM: + fprintf(stdout, "mov\t$%d, %s\n",t->attr.ival, *reg_ptr); + break; + default: + fprintf(stdout, "mov OTHER"); + } + } + /*case 1 + * t has a right child with label 0*/ + else if(t->r && t->r->label == 0) { + GEN_EXPR(t->l); + if (t->r && t->r->type == INT) { + fprintf(stdout, "op\t$%d,\n", t->r->attr.ival); + fprintf(stdout, "op\t$%d,%s\n", t->r->attr.ival, *reg_ptr); + } + } + /*case 2 + * 1 <= t->l->label < t->r->label AND t->l->lable < reg_cnt*/ + else if ((t->l->label <= 1 && t->l->label < t->r->label) + && t->l->label < reg_cnt) { + + REG_SWAP + GEN_EXPR(t->l); + REG_POP + GEN_EXPR(t->r); + fprintf(stdout, "op\t%s, %s\n", *(reg_ptr + 1), *reg_ptr); + REG_PUSH + REG_SWAP + } + /*case 3 + * 1 <= t->r->label <= t->l->label */ + else if (t->r->label <= 1 && t->r->label <= t->l->label) { + GEN_EXPR(t->l); + REG_POP + GEN_EXPR(t->r); + fprintf(stdout, "op\t%s, %s\n", *reg_ptr, *(reg_ptr + 1)); + REG_PUSH + } + /*case 4 + *t->l->label, t->r->label >= reg_cnt*/ + else if (t->l->label >= reg_cnt && t->r->label >= reg_cnt){ + /*TODO implement case 4*/ + yyerror("CASE 4 of gen_expr() NOT IMPLEMENTED\n"); + } else { + yyerror("NOT ONE OF DEFINED CASES [gen_expr()]\n"); + } + } void gen_statement(t) |