eeprom.c File Reference

EEPROM support. More...

Functions
eeprom_type_t	eeprom_present (void)
	Probe the EEPROM interface on the cartridge. More...
size_t	eeprom_total_blocks (void)
	Determine how many blocks of EEPROM exist on the cartridge. More...
void	eeprom_read (uint8_t block, uint8_t *dest)
	Read a block from EEPROM. More...
uint8_t	eeprom_write (uint8_t block, const uint8_t *src)
	Write a block to EEPROM. More...
void	eeprom_read_bytes (uint8_t *dest, size_t start, size_t len)
	Read a buffer of bytes from EEPROM. More...
void	eeprom_write_bytes (const uint8_t *src, size_t start, size_t len)
	Write a buffer of bytes to EEPROM. More...

Detailed Description

EEPROM support.

Function Documentation

eeprom_present()

eeprom_type_t eeprom_present

(

void

)

Probe the EEPROM interface on the cartridge.

Inspect the identifier half-word of the EEPROM status response to determine which EEPROM save type is available (if any).

Returns

which EEPROM type was detected on the cartridge.

eeprom_total_blocks()

size_t eeprom_total_blocks

(

void

)

Determine how many blocks of EEPROM exist on the cartridge.

Returns

0 if EEPROM was not detected or the number of EEPROM 8-byte save blocks available.

eeprom_read()

void eeprom_read	(	uint8_t	block,
		uint8_t *	dest
	)

Read a block from EEPROM.

Parameters

[in]	block	Block to read data from. Joybus accesses EEPROM in 8-byte blocks.
[out]	dest	Destination buffer for the eight bytes read from EEPROM.

eeprom_write()

uint8_t eeprom_write	(	uint8_t	block,
		const uint8_t *	src
	)

Write a block to EEPROM.

Parameters

[in]	block	Block to write data to. Joybus accesses EEPROM in 8-byte blocks.
[in]	src	Source buffer for the eight bytes of data to write to EEPROM.

Returns

the EEPROM status byte

eeprom_read_bytes()

void eeprom_read_bytes	(	uint8_t *	dest,
		size_t	start,
		size_t	len
	)

Read a buffer of bytes from EEPROM.

This is a high-level convenience helper that abstracts away the one-at-a-time EEPROM block access pattern.

Parameters

[out]	dest	Destination buffer to read data into
[in]	start	Byte offset in EEPROM to start reading data from
[in]	len	Byte length of data to read into buffer

eeprom_write_bytes()

void eeprom_write_bytes	(	const uint8_t *	src,
		size_t	start,
		size_t	len
	)

Write a buffer of bytes to EEPROM.

This is a high-level convenience helper that abstracts away the one-at-a-time EEPROM block access pattern.

Each EEPROM block write takes approximately 15 milliseconds; this operation may block for a while with large buffer sizes:

• 4k EEPROM: 64 blocks * 15ms = 960ms!
• 16k EEPROM: 256 blocks * 15ms = 3840ms!

You may want to pause audio before calling this.

Parameters

[in]	src	Source buffer containing data to write
[in]	start	Byte offset in EEPROM to start writing data to
[in]	len	Byte length of the src buffer