fvm/src/as_analyzer.c

#include "as_analyzer.h"

#include <stddef.h>
#include <string.h>

const char * compose_section_label(allocator_t alct, const char * section, const char * name) {
    size_t section_len = strlen(section);
    size_t name_len = strlen(name);
    size_t sz = section_len + name_len;
    char * buf = allocate(alct, sz + 1);
    memcpy(buf, section, section_len);
    memcpy(buf + section_len, name, name_len);
    buf[sz] = '\0';
    return buf;
}

void process_section_label(allocator_t alct, prog_t prog) {
    const char * section = "";
    stmt_t* stmts = prog->stmts->stmts;
    for (size_t i = 0; ; i++) {
        if (stmts[i] == NULL) break;
        if (stmts[i]->label == NULL) continue;
        const char* name = stmts[i]->label->name;
        if (name[0] == '.') {
            stmts[i]->label->name = compose_section_label(alct, section, name);
        } else {
            section = name;
            continue;
        }
    }
}

size_t instr_size(instr_t instr) {
    return op_size(instr->op);
}

struct sym_table new_sym_table(allocator_t alct) {
    struct sym_table tbl;
    tbl.cap = 16;
    tbl.size = 0;
    tbl.buf = allocate(alct, sizeof(struct sym_table_entry) * 16);
    return tbl;
}

void sym_table_add(allocator_t alct, struct sym_table* tbl, const char* name, int pos) {
    if (tbl->cap == tbl->size) {
        void *old_buf = tbl->buf;
        tbl->buf = allocate(alct, sizeof(struct sym_table_entry) * tbl->cap * 2);
        memcpy(tbl->buf, old_buf, sizeof(struct sym_table_entry) * tbl->cap);
        tbl->cap = tbl->cap * 2;
    }
    tbl->buf[tbl->size] = (struct sym_table_entry){.name = name, .offset = pos,};
    tbl->size += 1;
}

struct sym_table analyze_prog(allocator_t alct, prog_t prog) {
    process_section_label(alct, prog);
    stmt_t * stmts = prog->stmts->stmts;
    struct sym_table tbl = new_sym_table(alct);
    size_t cur_pos = 0;
    for (int i = 0; ; i++) {
        if (stmts[i] == NULL) break;
        stmt_t stmt = stmts[i];
        if (stmt->label) {
            sym_table_add(alct, &tbl, stmt->label->name, cur_pos);
        }
        if (stmt->instr) {
            cur_pos += instr_size(stmt->instr);
        }
    }
    return tbl;
}