//---
//	fxBoot:fs:smemfs:read - Casio SMEM read primtive
//---
#include "fxBoot/fs/smemfs.h"
#include <gint/std/string.h>
#include <gint/bfile.h>
#include <gint/gint.h>

/* external symbols */
extern uint32_t (*cpu_setVBR)(uint32_t vbr, void (*conf_intc)(int), int arg);

/* world information */
extern void *kernel_env_casio;
extern void *kernel_env_gint;
extern void *gint_switch_to_world(void *buffctx);


/* generate_abolute_path(): Generate abolute path

   This function will generate the absolute path of a file because Casio's open
   primitive doesn't handle cannonical path */
static void generate_absolute_path(uint16_t *pathname,
					struct smemfs_inode *inode, int *pos)
{
	/* Check root inode */
	if (inode == NULL) {
		memcpy(pathname, u"\\\\fls0", 12);
		*pos = 6;
		return;
	}

	/* Get the parent inode name */
	generate_absolute_path(pathname, inode->parent, pos);

	/* Insert the file name */
	pathname[(*pos)++] = '\\';
	for (int i = 0; inode->name[i] != '\0'; ) {
		pathname[*pos] = inode->name[i];
		*pos = *pos + 1;
		i = i + 1;
	}
	pathname[*pos] = '\0';
}

/* smemfs_read(): Read primitive */
ssize_t	smemfs_pread(struct smemfs_inode *inode,
					void *buf, size_t count, off_t pos)
{
	uint16_t pathname[64];
	ssize_t read;
	int handle;

	if (inode == NULL)
		return (-1);

	/* Generate the absolute pathname with FONTCHARACTER format */
	generate_absolute_path(pathname, inode, &handle);

	/* Switch from gint to the OS after a short wait */
	gint_switch_to_world(kernel_env_casio);

	/* Open, read and close the file using Casio's OS syscall */
	read = -1;
	handle = BFile_Open(pathname, BFile_ReadOnly);
	if (handle >= 0) {
		read = BFile_Read(handle, buf, count, pos);
		BFile_Close(handle);
	}

	/* Then switch back to gint once the OS finishes working */
	gint_switch_to_world(kernel_env_gint);

	/* return the number of byte readed */
	return (read);
}