sram.h File Reference

SRAM (Static RAM used for save backup) support. More...

#include "mapper.h"

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Macros
#define	SRAM_CONTROL   MAPPER_BASE
#define	SRAM_BASE   0x200001

Functions
void	SRAM_enable (void)
	Enable SRAM in Read Write mode.
void	SRAM_enableRO (void)
	Enable SRAM in Read Only mode.
void	SRAM_disable (void)
	Disable SRAM.
u8	SRAM_readByte (u32 offset)
	Read a byte from the SRAM.
u16	SRAM_readWord (u32 offset)
	Read a word from the SRAM.
u32	SRAM_readLong (u32 offset)
	Read a long from the SRAM.
void	SRAM_writeByte (u32 offset, u8 val)
	Write a byte to the SRAM.
void	SRAM_writeWord (u32 offset, u16 val)
	Write a word to the SRAM.
void	SRAM_writeLong (u32 offset, u32 val)
	Write a long to the SRAM.

Detailed Description

SRAM (Static RAM used for save backup) support.

Author

Chilly Willy & Stephane Dallongeville

Date

08/2012

This unit provides methods to read from or write to SRAM.
By default we suppose SRAM is 8bit and connected to odd address.
You can change to even address by changing SRAM_BASE from 0x200001 to 0x200000 and rebuild the library.

Informations about SRAM (taken from Segaretro.org):
The regions specified by 0xA130F9-0xA130FF (0x200000-0x3FFFFF) can be either ROM or RAM and can be write-protected.
Here is the layout of the register as far as I know:

7 6 5 4 3 2 1 0
+--------------------—+
|??|??|??|??|??|??|WP|MD|
+--------------------—+

MD: Mode – 0 = ROM, 1 = RAM
WP: Write protect – 0 = writable, 1 = not writable

Function Documentation

SRAM_readByte()

u8 SRAM_readByte

(

u32

offset

)

Read a byte from the SRAM.

Parameters

offset

Offset where we want to read.

Returns

value.

SRAM_readLong()

u32 SRAM_readLong

(

u32

offset

)

Read a long from the SRAM.

Parameters

offset

Offset where we want to read.

Returns

value.

SRAM_readWord()

u16 SRAM_readWord

(

u32

offset

)

Read a word from the SRAM.

Parameters

offset

Offset where we want to read.

Returns

value.

SRAM_writeByte()

void SRAM_writeByte	(	u32	offset,
		u8	val )

Write a byte to the SRAM.

Parameters

offset	Offset where we want to write.
val	Value wto write.

SRAM_writeLong()

void SRAM_writeLong	(	u32	offset,
		u32	val )

Write a long to the SRAM.

Parameters

offset	Offset where we want to write.
val	Value wto write.

SRAM_writeWord()

void SRAM_writeWord	(	u32	offset,
		u16	val )

Write a word to the SRAM.

Parameters

offset	Offset where we want to write.
val	Value wto write.