A part of building blocks for inter-memory transfer, dedicated to ROM / RAM access.

Building blocks for copying and transferring data between different types of memory devices. More...

Collaboration diagram for A part of building blocks for inter-memory transfer, dedicated to ROM / RAM access.:

Files
file	mem_rw.h
	Stream like access functions for ROM / RAM.

Functions
bool	mem_is_opened (void)
	Tests whether ROM/RAM accessor is opened or not.
void	mem_open (uint8_t *loc)
	Open ROM/RAM accessor.
void	mem_close (void)
	Close ROM/RAM accessor.
void	mem_dup (uint16_t offset, size_t len)
	Duplicate a sequence of bytes beginning at the specified offset in the output stream at the current position or later.
uint8_t *	mem_ptr (void)
	Get current position of ROM/RAM accessor.
bool	mem_is_in_free_area (uint8_t *p, size_t len)
	Tests whether the specified range is in free area.
void	mem_write_chunk (const uint8_t *src, size_t len)
	Write a chunk to RAM.
void	mem_read_chunk (uint8_t *dst, size_t len)
	Read a chunk from ROM/RAM.
void	mem_write_byte (uint8_t x)
	Write an octet to RAM.
uint8_t	mem_read_byte (void)
	Read an octet from ROM/RAM.

Detailed Description

Building blocks for copying and transferring data between different types of memory devices.

#include <mem_rw.h>

Function Documentation

mem_is_opened()

bool mem_is_opened

(

void

)

Tests whether ROM/RAM accessor is opened or not.

Returns

whether ROM/RAM accessor is opened or not.

mem_open()

void mem_open

(

uint8_t *

loc

)

Open ROM/RAM accessor.

Parameters

loc	base address.

Precondition

!mem_is_opened()

mem_close()

void mem_close

(

void

)

Close ROM/RAM accessor.

Precondition

mem_is_opened()

mem_dup()

void mem_dup	(	uint16_t	offset,
		size_t	len
	)

Duplicate a sequence of bytes beginning at the specified offset in the output stream at the current position or later.

A data in range of [p - offset, p - offset + len) of RAM/ROM will be copied to [p, p + len), where p is current position. If both area overlaps, repetition is occur.

For example, if the byte in p-1 is X, then mem_dup(1, 3) copies X to p, p+1, p+2 and p is increased by 3.

Parameters

offset	distance from the current position.
length	length in bytes.

Precondition

mem_is_opened()

mem_ptr()

uint8_t * mem_ptr

(

void

)

Get current position of ROM/RAM accessor.

Returns

current position.

Precondition

mem_is_opened()

mem_is_in_free_area()

bool mem_is_in_free_area	(	uint8_t *	p,
		size_t	len
	)

Tests whether the specified range is in free area.

Parameters

p	base address of the range.
len	length the range in bytes.

Returns

true if the range is in [0xc000, (HIMEM)), otherwise false.

Note

This function just checks that the specified area is in range of free area. No data is written to the memory.

Page #0..#2 (0x0000..0xbfff) are ROM.

HIMEM points the lowest address of reserved area. (out of free area)

DATA segment, HEAP, and stack area are in the free area.

Address 0xffff is not memory, that is "extended slot selector" register.

Attention

When writing to memory, the stack area or work area is overwritten (broken) if it intersects the destination area. Unfortunately, however, the library cannot determine the proper boundaries. This must be addressed by the application programmer.

mem_write_chunk()

void mem_write_chunk	(	const uint8_t *	src,
		size_t	len
	)

Write a chunk to RAM.

Parameters

src	source base address.
len	number of bytes to be copied.

Precondition

mem_is_opened()

Note

The destination [mem, mem+len) must be in range of [0xc000, (HIMEM)), where mem is the current position.

mem_read_chunk()

void mem_read_chunk	(	uint8_t *	dst,
		size_t	len
	)

Read a chunk from ROM/RAM.

Parameters

dst	destination base address.
len	number of bytes to be copied.

Precondition

mem_is_opened()

Note

The destination [dst, dst+len) must be in range of [0xc000, (HIMEM)).

mem_write_byte()

void mem_write_byte

(

uint8_t

x

)

Write an octet to RAM.

Parameters

x	a value to be written to RAM.

Note

The current position must be in range of [0xc000, (HIMEM)).

mem_read_byte()

uint8_t mem_read_byte

(

void

)

Read an octet from ROM/RAM.

Returns

a value read from ROM/RAM.

Precondition

mem_is_opened()