Filter: Instruction codes named as enum

The two-letter instructions were quite messy but they could be easily
read from memory dumps. Now GDB (since 2012) supports pretty printing
enum values and GCC checks the switch construction for missing enum
values so we are converting the nice two-byte values to enums.

Anyway, the enum still keeps the old two-byte values to be able to read
the instruction codes even without GDB from plain memory dump.

filter/filter.h

@@ -14,9 +14,67 @@
 #include "nest/route.h"
 #include "nest/attrs.h"
 
+/* Filter instruction types */
+
+#define FI__TWOCHAR(a,b)	((a<<8) | b)
+#define FI__LIST \
+  F(FI_COMMA,			  0, ',') \
+  F(FI_ADD,			  0, '+') \
+  F(FI_SUBTRACT,		  0, '-') \
+  F(FI_MULTIPLY,		  0, '*') \
+  F(FI_DIVIDE,			  0, '/') \
+  F(FI_AND,			  0, '&') \
+  F(FI_OR,			  0, '|') \
+  F(FI_PAIR_CONSTRUCT,		'm', 'p') \
+  F(FI_EC_CONSTRUCT,		'm', 'c') \
+  F(FI_LC_CONSTRUCT,		'm', 'l') \
+  F(FI_NEQ,			'!', '=') \
+  F(FI_EQ,			'=', '=') \
+  F(FI_LT,			  0, '<') \
+  F(FI_LTE,			'<', '=') \
+  F(FI_NOT,			  0, '!') \
+  F(FI_MATCH,			  0, '~') \
+  F(FI_NOT_MATCH,		'!', '~') \
+  F(FI_DEFINED,			'd', 'e') \
+  F(FI_SET,			  0, 's') \
+  F(FI_CONSTANT,		  0, 'c') \
+  F(FI_VARIABLE,		  0, 'V') \
+  F(FI_CONSTANT_INDIRECT,	  0, 'C') \
+  F(FI_PRINT,			  0, 'p') \
+  F(FI_CONDITION,		  0, '?') \
+  F(FI_NOP,			  0, '0') \
+  F(FI_PRINT_AND_DIE,		'p', ',') \
+  F(FI_RTA_GET,			  0, 'a') \
+  F(FI_RTA_SET,			'a', 'S') \
+  F(FI_EA_GET,			'e', 'a') \
+  F(FI_EA_SET,			'e', 'S') \
+  F(FI_PREF_GET,		  0, 'P') \
+  F(FI_PREF_SET,		'P', 'S') \
+  F(FI_LENGTH,			  0, 'L') \
+  F(FI_IP,			'c', 'p') \
+  F(FI_AS_PATH_FIRST,		'a', 'f') \
+  F(FI_AS_PATH_LAST,		'a', 'l') \
+  F(FI_AS_PATH_LAST_NAG,	'a', 'L') \
+  F(FI_RETURN,			  0, 'r') \
+  F(FI_CALL,			'c', 'a') \
+  F(FI_CLEAR_LOCAL_VARS,	'c', 'V') \
+  F(FI_SWITCH,			'S', 'W') \
+  F(FI_IP_MASK,			'i', 'M') \
+  F(FI_EMPTY,			  0, 'E') \
+  F(FI_PATH_PREPEND,		'A', 'p') \
+  F(FI_CLIST_ADD_DEL,		'C', 'a') \
+  F(FI_ROA_CHECK,		'R', 'C')
+
+enum f_instruction_code {
+#define F(c,a,b) \
+  c = FI__TWOCHAR(a,b),
+FI__LIST
+#undef F
+} PACKED;
+
 struct f_inst {		/* Instruction */
   struct f_inst *next;	/* Structure is 16 bytes, anyway */
-  u16 code;
+  enum f_instruction_code fi_code;
   u16 aux;
   union {
     int i;
@@ -75,15 +133,32 @@ struct f_val {
   } val;
 };
 
+struct f_dynamic_attr {
+  int type;
+  int f_type;
+  int ea_code;
+};
+
+struct f_static_attr {
+  int f_type;
+  int sa_code;
+  int readonly;
+};
+
 struct filter {
   char *name;
   struct f_inst *root;
 };
 
-struct f_inst *f_new_inst(void);
-struct f_inst *f_new_dynamic_attr(int type, int f_type, int code);	/* Type as core knows it, type as filters know it, and code of dynamic attribute */
+struct f_inst *f_new_inst(enum f_instruction_code fi_code);
+struct f_inst *f_new_inst_da(enum f_instruction_code fi_code, struct f_dynamic_attr da);
+struct f_inst *f_new_inst_sa(enum f_instruction_code fi_code, struct f_static_attr sa);
+static inline struct f_dynamic_attr f_new_dynamic_attr(int type, int f_type, int code) /* Type as core knows it, type as filters know it, and code of dynamic attribute */
+{ return (struct f_dynamic_attr) { .type = type, .f_type = f_type, .ea_code = code }; }   /* f_type currently unused; will be handy for static type checking */
+static inline struct f_static_attr f_new_static_attr(int f_type, int code, int readonly)
+{ return (struct f_static_attr) { .f_type = f_type, .sa_code = code, .readonly = readonly }; }
 struct f_tree *f_new_tree(void);
-struct f_inst *f_generate_complex(int operation, int operation_aux, struct f_inst *dyn, struct f_inst *argument);
+struct f_inst *f_generate_complex(int operation, int operation_aux, struct f_dynamic_attr da, struct f_inst *argument);
 struct f_inst *f_generate_roa_check(struct symbol *sym, struct f_inst *prefix, struct f_inst *asn);