NASM源码阅读笔记

typedef struct {
    /*
     * Called at the start of a pass; given a file name, the number
     * of the pass, an error reporting function, an evaluator
     * function, and a listing generator to talk to.
     */
    void (*reset) (char *, int, efunc, evalfunc, ListGen *);

    /*
     * Called to fetch a line of preprocessed source. The line
     * returned has been malloc'ed, and so should be freed after
     * use.
     */
    char *(*getline) (void);

    /*
     * Called at the end of a pass.
     */
    void (*cleanup) (int);
} Preproc;

typedef struct {                    /* an instruction itself */
    char *label;                    /* the label defined, or NULL */
    int prefixes[MAXPREFIX];       /* instruction prefixes, if any */
    int nprefix;                    /* number of entries in above */
    int opcode;                     /* the opcode - not just the string */
    int condition;                  /* the condition code, if Jcc/SETcc */
    int operands;                   /* how many operands? 0-3 
                                    * (more if db et al) */
    operand oprs[3];        /* the operands, defined as above */
    extop *eops;                    /* extended operands */
    int eops_float;                /* true if DD and floating */
    long times;                     /* repeat count (TIMES prefix) */
    int forw_ref;                   /* is there a forward reference? */
} insn;

void parser_global_info (struct ofmt *output, loc_t *locp);
insn *parse_line (int pass, char *buffer, insn *result,
               efunc error, evalfunc evaluate, ldfunc ldef);
void cleanup_insn (insn *instruction);

long insn_size (long segment, long offset, int bits, unsigned long cpu,
             insn *instruction, efunc error);
long assemble (long segment, long offset, int bits, unsigned long cpu,
            insn *instruction, struct ofmt *output, efunc error,
            ListGen *listgen);

/*
 * Expression-evaluator datatype. Expressions, within the
 * evaluator, are stored as an array of these beasts, terminated by
 * a record with type==0. Mostly, it's a vector type: each type
 * denotes some kind of a component, and the value denotes the
 * multiple of that component present in the expression. The
 * exception is the WRT type, whose `value' field denotes the
 * segment to which the expression is relative. These segments will
 * be segment-base types, i.e. either odd segment values or SEG_ABS
 * types. So it is still valid to assume that anything with a
 * `value' field of zero is insignificant.
 */
typedef struct {
    long type;                             /* a register, or EXPR_xxx */
    long value;                            /* must be >= 32 bits */
} expr;

extern char lprefix[PREFIX_MAX];
extern char lpostfix[PREFIX_MAX];

int lookup_label (char *label, long *segment, long *offset);
int is_extern (char *label);
void define_label (char *label, long segment, long offset, char *special,
                   int is_norm, int isextrn, struct ofmt *ofmt, efunc error);
void redefine_label (char *label, long segment, long offset, char *special,
                   int is_norm, int isextrn, struct ofmt *ofmt, efunc error);
void define_common (char *label, long segment, long size, char *special,
                    struct ofmt *ofmt, efunc error);
void declare_as_global (char *label, char *special, efunc error);
int init_labels (void);
void cleanup_labels (void);

ListGen nasmlist = {
    list_init,
    list_cleanup,
    list_output,
    list_line,
    list_uplevel,
    list_downlevel
};

int float_const (char *number, long sign, unsigned char *result, int bytes,
 efunc error);