/* Copyright (c) 2024 Freya Murphy */

#ifndef __GEN_H__
#define __GEN_H__

#include <mlimits.h>
#include <mips.h>
#include <stdint.h>

#include "parse.h"
#include "tab.h"

// predefine
struct generator;

///
/// a section
///
struct section {
	// name
	struct string name;

	// alignment
	size_t align;

	// data
	char *data;
	size_t len;
	size_t size;

	// permissions
	bool read;
	bool write;
	bool execute;

	/// reference table
	struct reference_table reftab;
};

void section_free(struct section *section);

///
/// instruction generation state
///

struct gen_ins_state {
	// rd,rs,rt
	enum mips32_register rd;
	enum mips32_register rs;
	enum mips32_register rt;

	// fs,ft
	enum mips32_fp_register fs;
	enum mips32_fp_register ft;
	enum mips32_fp_register fd;

	// immd
	uint16_t immd;  // 16 bit

	// cc
	uint16_t cc;    // 3 bit

	// code
	uint32_t code;  // 5 bit

	// pos
	uint32_t pos;   // 5 bit

	// size
	uint32_t size;  // 5 bit - 1

	// hb
	bool hb; // 1 bit - 1

	// index
	uint32_t index;

	// hint
	uint32_t hint;

	// offset(base)
	uint16_t offset; // 16 bit
	enum mips32_register base;

	// target
	uint32_t target;

	// current referencd label
	struct string *label;
};

struct gen_ins_override {
	enum mips32_register reg;
	enum mips32_fp_register fpreg;
	uint32_t immd;
};

///
/// grammer type
///

enum grammer_type {
	// registers
	GMR_RD,
	GMR_RS,
	GMR_RT,
	GMR_INDEX_BASE,
	// fp registers
	GMR_FS,
	GMR_FT,
	GMR_FD,
	// numeric fields
	GMR_IMMD,
	GMR_CC,
	GMR_CODE,
	GMR_POS,
	GMR_SIZE,
	GMR_HB,
	GMR_HINT,
	// addresses
	GMR_OFFSET,
	GMR_OFFSET_BASE,
	GMR_TARGET,
	GMR_HI,
	GMR_LO,
};

///
/// generates assembley
/// from a parser stream
///
struct generator {
	struct parser parser;

	// current instruction table
	size_t instructions_len;
	union mips32_instruction *instructions;

	// current grammer table
	size_t grammers_len;
	struct mips32_grammer *grammers;

	// segments
	size_t sections_len;
	size_t sections_size;
	struct section *sections;

	// current section
	struct section *current;

	// symbol table
	struct symbol_table symtab;
};

/* generate the input as mips32r6 */
int generate_mips32r6(struct generator *gen);
/* run codegen with the mips32r2 specification */
int generate_mips32r2(struct generator *gen);
/* run codegen with the mips32r6 specification */
int generate_mips1(struct generator *gen);

/* initalize a generator */
int generator_init(const char *file, struct generator *gen);

/* free a generator */
void generator_free(struct generator *gen);

#endif /* __GEN_H__ */