/*
 * a.h — w6a-private header. Modelled on Plan 9 cmd/6a/a.h, trimmed
 * to the instruction subset that w6c emits.
 *
 * w6a is line-oriented and has no preprocessor: each non-blank, non-
 * label line is one instruction. We read the whole file into a list
 * of `Aprog`s, then encode and emit ELF64.
 */
#ifndef SIX_A_H
#define SIX_A_H

#include "6.out.h"
#include <stddef.h>
#include <stdint.h>
#include <stdio.h>

typedef int8_t   i8;
typedef int16_t  i16;
typedef int32_t  i32;
typedef int64_t  i64;
typedef uint8_t  u8;
typedef uint16_t u16;
typedef uint32_t u32;
typedef uint64_t u64;

typedef struct Aoperand Aoperand;
typedef struct Aprog    Aprog;
typedef struct Asym     Asym;
typedef struct Areloc   Areloc;
typedef struct Asm      Asm;

struct Aoperand {
	int	type;	/* D_NONE, D_AX..D_R15, D_CONST, D_INDIR, D_EXTERN, D_BRANCH */
	int	reg;	/* base register for D_INDIR */
	i64	offset;	/* immediate or displacement */
	const char *sym;
};

struct Aprog {
	int	as;	/* opcode (A_*) */
	Aoperand from;
	Aoperand to;
	int	line;
	const char *label;	/* label preceding this prog, if any */
	Aprog	*link;
	/* for A_DATA: raw payload bytes interned by the parser */
	u8	*bytes;
	u64	nbytes;
};

struct Asym {
	const char *name;
	int	defined;	/* 1 if we own its address */
	int	is_text;	/* if 1, address is in .text */
	int	is_data;	/* if 1, address is in .data (mutually exclusive with is_text) */
	int	is_global;	/* exported (TEXT) */
	u64	addr;		/* offset within section if defined */
	int	idx;		/* ELF symtab index, filled at emit time */
	Asym	*next;
};

struct Areloc {
	u64	off;	/* offset within the relocation's section */
	int	section;/* 0 = .text (most relocs), 1 = .data (DATAR) */
	int	kind;	/* R_X86_64_64 (1), R_X86_64_PC32 (2), R_X86_64_PLT32 (4) */
	Asym	*sym;
	i64	addend;
	Areloc	*next;
};

struct Asm {
	/* parser state */
	const char *file;
	const char *src;
	u64	srclen;
	u64	pos;
	int	line;

	/* program list */
	Aprog	*head, *tail;

	/* output text section */
	u8	*text;
	u64	textcap, textlen;

	/* output data section (writable). Empty unless any DATAW directive
	 * was seen; in that case obj.c emits an extra .data PROGBITS
	 * section with SHF_WRITE. */
	u8	*data;
	u64	datacap, datalen;

	/* symbols */
	Asym	*syms;
	Areloc	*relocs;

	int	errs;
};

/* lex.c / parse.c */
void	a_init(Asm*, const char *file, const char *src, u64 len);
int	a_parse(Asm*);

/* asm.c */
int	a_encode(Asm*);

/* obj.c */
int	a_emit_elf(Asm*, FILE *out);

/* helpers */
Asym	*a_intern(Asm*, const char *name);
void	a_emit_byte(Asm*, u8);
void	a_emit_u32(Asm*, u32);
void	a_emit_data_byte(Asm*, u8);
void	a_addreloc(Asm*, u64 off, int kind, Asym *s, i64 add);
void	a_addreloc_data(Asm*, u64 off, int kind, Asym *s, i64 add);

#endif