A part of building blocks for inter-memory transfer, dedicated to VRAM 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 VRAM access.:

Files
file	vmem_rw.h
	Stream like access functions for VRAM.

Functions
bool	vmem_is_opened (void)
	MSX Tests whether VRAM accessor is opened or not.
void	vmem_open (vmemptr_t loc)
	MSX Open VRAM accessor.
void	vmem_close (void)
	MSX Close VRAM accessor.
void	vmem_dup (uint16_t offset, size_t len)
	MSX Duplicate a byte sequence of VRAM starting from the specified offset to current position and later.
vmemptr_t	vmem_ptr (void)
	Get current position of VRAM accessor.
void	vmem_skip (size_t len)
	Advance the current position of VRAM accessor.
void	vmem_write_chunk (const uint8_t *src, uint16_t len)
	Write a chunk to VRAM.
void	vmem_read_chunk (uint8_t *dst, uint16_t len)
	Read a chunk from VRAM.

Detailed Description

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

#include <vmem_rw.h>

Function Documentation

vmem_is_opened()

bool vmem_is_opened

(

void

)

MSX Tests whether VRAM accessor is opened or not.

Returns

whether VRAM accessor is opened or not.

vmem_open()

void vmem_open

(

vmemptr_t

loc

)

MSX Open VRAM accessor.

Parameters

loc	base address.

Precondition

!vmem_is_opened()

vmem_close()

void vmem_close

(

void

)

MSX Close VRAM accessor.

Precondition

vmem_is_opened()

vmem_dup()

void vmem_dup	(	uint16_t	offset,
		size_t	len
	)

MSX Duplicate a byte sequence of VRAM starting from the specified offset to current position and later.

A data in range of [p - offset, p - offset + len) of VRAM 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 vmem_dup(1, 3) copies X to p, p+1, p+2 and p is increased by 3.

Parameters

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

Precondition

vmem_is_opened()

vmem_ptr()

vmemptr_t vmem_ptr

(

void

)

Get current position of VRAM accessor.

Returns

current position.

Precondition

vmem_is_opened()

Note

internal use only.

vmem_skip()

void vmem_skip

(

size_t

len

)

Advance the current position of VRAM accessor.

Parameters

len	number of bytes.

Precondition

vmem_is_opened()

vmem_write_chunk()

void vmem_write_chunk	(	const uint8_t *	src,
		uint16_t	len
	)

Write a chunk to VRAM.

Parameters

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

Precondition

vmem_set_write_address() has been called.

vmem_set_read_address() has not been called after vmem_set_write_address().

Note

internal use only.

vmem_read_chunk()

void vmem_read_chunk	(	uint8_t *	dst,
		uint16_t	len
	)

Read a chunk from VRAM.

Parameters

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

Precondition

vmem_set_read_address() has been called.

vmem_set_write_address() has not been called after vmem_set_read_address().

Note

internal use only.