#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <assert.h>

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <stdarg.h>

#include <elf.h>

//---
// Structure of CPU73050.dll
//---

/* First is an address to the list of register tables
     struct reg (*TABLE_LIST_ADDRESS)[][]
   (second-level arrays are not stored contiguously) */
uint32_t const TABLE_LIST_ADDRESS = 0x100903e0;
/* Just following is the list of peripheral modules
     struct module MODULE_LIST[]
   Unlike register tables this is not a pointer, it's the whole table */
uint32_t const MODULE_LIST = 0x100903e4;

/* Each module has the following structure (yet to be discovered entirely) */
struct module
{
	uint32_t pointer_to_name;
	uint32_t pointer_to_description;
	uint32_t unknown[28];
};
/* Each peripheral register has this structure */
struct reg
{
	uint32_t pointer_to_name;
	uint32_t pointer_to_description;
	uint32_t unknown_1;
	uint32_t address;
	uint32_t unknown_2[2];
	uint32_t data_size;
	uint32_t access_size;
	uint32_t unknown_3[2];

	uint32_t f1_other;
	uint32_t f1_u8;
	uint32_t f1_u16;
	uint32_t f1_u32;

	uint32_t f2_other;
	uint32_t f2_u8;
	uint32_t f2_u16;
	uint32_t f2_u32;

	uint32_t unknown_6[13];
};

//---
// ELF utilities
//---

void check_header(Elf32_Ehdr *h)
{
	/* Signature */
	assert(h->e_ident[EI_MAG0] == ELFMAG0);
	assert(h->e_ident[EI_MAG1] == ELFMAG1);
	assert(h->e_ident[EI_MAG2] == ELFMAG2);
	assert(h->e_ident[EI_MAG3] == ELFMAG3);
	/* Class */
	assert(h->e_ident[EI_CLASS] == ELFCLASS32);
	/* Little endian */
	assert(h->e_ident[EI_DATA] == ELFDATA2LSB);
	/* Must have a section table */
	assert(h->e_shoff != 0);
}

Elf32_Shdr *get_section(Elf32_Ehdr *h, int id)
{
	return (void *)h + h->e_shoff + id * h->e_shentsize;
}

/* Get data from virtual address by searching all sections */
void *get_virtual(Elf32_Ehdr *elf, uint32_t address)
{
	for(int id = 0; id < elf->e_shnum; id++)
	{
		/* Skip sections of uninteresting types */
		Elf32_Shdr *section = get_section(elf, id);
		int type = section->sh_type;
		if(type == SHT_NULL || type == SHT_STRTAB) continue;

		/* Check if in bounds of virtual address */
		int32_t offset = address - section->sh_addr;
		if(offset < 0 || offset >= (int32_t)section->sh_size) continue;

		return (void *)elf + section->sh_offset + offset;
	}

	return NULL;
}

void print_sections(Elf32_Ehdr *elf)
{
	Elf32_Shdr *strtable_section = get_section(elf, elf->e_shstrndx);
	char const *strtable = (void *)elf + strtable_section->sh_offset;

	printf("Sections:\n");
	printf("     Name      Size      Virtual\n");

	for(int id = 0; id < elf->e_shnum; id++)
	{
		Elf32_Shdr *section = get_section(elf, id);
		int type = section->sh_type;
		if(type == SHT_NULL || type == SHT_STRTAB) continue;

		char const *name = strtable + section->sh_name;
		printf(" %2d  %-8s  %08x  %08x\n", id, name, section->sh_size,
			section->sh_addr);
	}

}

//---
// Data analysis heuristics
//---

int valid_looking_string(uint8_t const *str)
{
	int i = 0;
	while(i < 256 && str[i] >= 32 && str[i] <= 0x7f) i++;
	return (i > 0) && (i < 256) && !str[i];
}

int valid_looking_module(Elf32_Ehdr *elf, struct module *m)
{
	/* Check that there are valid printable ASCII name and description */
	if((m->pointer_to_name        & 0xfff00000) != 0x10000000) return 0;
	if((m->pointer_to_description & 0xfff00000) != 0x10000000) return 0;

	uint8_t const *name = get_virtual(elf, m->pointer_to_name);
	if(!valid_looking_string(name)) return 0;

	return 1;
}

int valid_looking_reg(Elf32_Ehdr *elf, struct reg *r)
{
	/* Check that there is a valid name */
	if((r->pointer_to_name        & 0xfff00000) != 0x10000000) return 0;
	if((r->pointer_to_description & 0xfff00000) != 0x10000000) return 0;

	/* Check that the name is printable ASCII */
	uint8_t const *name = get_virtual(elf, r->pointer_to_name);
	if(!valid_looking_string(name)) return 0;

	return 1;
}

//---
//  Analysis of CPU73050.elf to find SH7305 register lists
//---

void print_module(Elf32_Ehdr *elf, struct module *m)
{
	if(m == NULL)
	{
		printf("  (Virtual)  Name:       Description:\n");
		return;
	}

	char const *name = get_virtual(elf, m->pointer_to_name);
	char const *desc = get_virtual(elf, m->pointer_to_description);
	printf("  %-10s  %s\n", name, desc);
}

void print_reg_f(char str[8][9], ...)
{
	va_list args;
	va_start(args, str);

	for(int i = 0; i < 8; i++)
	{
		uint32_t ptr = va_arg(args, uint32_t);
		if(ptr == 0) sprintf(str[i], "%-8s", "");
		else sprintf(str[i], "%08x", ptr);
	}

	va_end(args);
}

void print_reg(Elf32_Ehdr *elf, struct reg *r)
{
	if(r == NULL)
	{
		printf("  (Virtual)  Name:            Address:  Data size:  "
			"Access size:  f1_u8    f2_u8    f1_u16   f2_u16   "
			"f1_u32   f2_u32   f1_def   f2_def    Description:\n");
		return;
	}

	char const *name = get_virtual(elf, r->pointer_to_name);
	char const *desc = get_virtual(elf, r->pointer_to_description);

	char s1[9], s2[9];

	sprintf(s1, "%08x", r->data_size);
	if(r->data_size == 1) sprintf(s1, "u8");
	if(r->data_size == 2) sprintf(s1, "u16");
	if(r->data_size == 4) sprintf(s1, "u32");

	sprintf(s2, "%08x", r->access_size);
	if(r->access_size == 1) sprintf(s2, "u8");
	if(r->access_size == 2) sprintf(s2, "u16");
	if(r->access_size == 4) sprintf(s2, "u32");

	char fstr[8][9];
	print_reg_f(fstr, r->f1_u8, r->f2_u8, r->f1_u16, r->f2_u16, r->f1_u32,
		r->f2_u32, r->f1_other, r->f2_other);

	printf("  %-16s %08x  %-8s    %-8s      ", name, r->address, s1, s2);
	for(int i = 0; i < 8; i++) printf("%s ", fstr[i]);
	printf(" %s\n", desc);
}

int main(int argc, char **argv)
{
	int e;
	assert(sizeof(struct module) == 0x78);
	assert(sizeof(struct reg) == 0x7c);

	char const *input = (argc == 1) ? "CPU73050.elf" : argv[1];
	printf("Extracting register lists from %s\n\n", input);

	int fd = open(input, O_RDONLY);
	if(fd < 0) { perror("open"); return 1; }

	struct stat statbuf;
	e = fstat(fd, &statbuf);
	if(e < 0) { perror("fstat"); close(fd); return 1; }

	void *buf = malloc(statbuf.st_size);
	if(!buf) { perror("malloc"); close(fd); return 1; }

	e = read(fd, buf, statbuf.st_size);
	close(fd);
	if(e != statbuf.st_size) { perror("read"); return 1; }

	/** Parse ELF header **/

	Elf32_Ehdr *elf = buf;
	check_header(elf);
	print_sections(elf);

	/** List modules **/

	struct module *modules = get_virtual(elf, MODULE_LIST);
	printf("\nModule list:\n");
	print_module(elf, NULL);

	for(int i = 0; 1; i++)
	{
		struct module *m = &modules[i];
		if(!valid_looking_module(elf, m)) break;
		printf("  %08x ", MODULE_LIST + i*(int)sizeof(struct module));
		print_module(elf, m);
	}

	/** List virtual addresses of tables **/

	uint32_t TABLE_LIST = *(uint32_t *)get_virtual(elf,TABLE_LIST_ADDRESS);
	uint32_t *tables = get_virtual(elf, TABLE_LIST);

	printf("\nThe table list at %08x (HARDCODED) has these tables:\n",
		TABLE_LIST);

	for(int i = 0; tables[i]; i++)
	{
		printf("  %08x", tables[i]);
		if((i % 8) == 7 || !tables[i+1]) printf("\n");
	}

	/** List contents of tables **/

	int total = 0;

	for(int i = 0; tables[i]; i++)
	{
		uint32_t entry = tables[i];
		struct reg *table = get_virtual(elf, entry);

		char header[256];
		sprintf(header, "\nIn the table at %08x:\n", entry);
		int header_printed = 0;

		int k = 0;
		while(valid_looking_reg(elf, table + k))
		{
			if(!header_printed)
			{
				printf("%s", header);
				print_reg(elf, NULL);
				header_printed = 1;
			}

			struct reg *r = table + k;
			printf("  %08x ", entry + k * (int)sizeof(struct reg));
			print_reg(elf, r);

			k++;
		}
		total += k;

		if(k == 0)
		{
			/* Try to view it as a string */
			uint8_t const *str = (void *)table;
			if(valid_looking_string(str))
			{
				printf("\nThe table at %08x is a string:\n",
					entry);
				printf("  %s\n", str);
			}
			else printf("\nNothing in the table at %08x\n", entry);
		}
	}

	free(elf);
	return 0;
}