ra8_fs_backend_t Struct Reference

Block-device interface that ra8_fs runs on top of. More...

#include <ra8_fs_types.h>

Data Fields
ra8_err_t(*	read_block )(void *ctx, uint64_t lba, uint32_t count, uint8_t *buf)
	Read count consecutive blocks starting at lba.
ra8_err_t(*	write_block )(void *ctx, uint64_t lba, uint32_t count, const uint8_t *buf)
	Write count consecutive blocks starting at lba.
ra8_err_t(*	get_capacity )(void *ctx, uint64_t *block_count, uint32_t *block_size)
	Report the device size.
ra8_err_t(*	erase_blocks )(void *ctx, uint64_t lba, uint64_t count)
	OPTIONAL: bulk-erase count blocks at lba to all-zero bytes.
void *	ctx
	Caller-owned context passed back into the function pointers.

Detailed Description

Block-device interface that ra8_fs runs on top of.

Three function pointers + a context cookie. Each implementation (SDHI, USB MSC, mock) fills these in and passes the struct to ra8_fs_mount().

LBAs and the block count are 64-bit so media past the 32-bit-LBA reach (2 TiB at 512-byte blocks) are addressable end to end – through the mount's partition base, the GPT parser and every cluster computation (#683). The block size is the medium's real sector size: 512-byte and 4096-byte-native (4Kn) devices are both supported, 1024/2048 included.

Warning

The 4Kn and beyond-2-TiB paths are verified by host-side simulation against fake backends only – no such medium has been on the bench. The 512-byte, sub-2-TiB path is the hardware-proven one.

Invariant

read_block, write_block, get_capacity are non-NULL for a usable backend. erase_blocks and ctx may be NULL.

Definition at line 149 of file ra8_fs_types.h.

Field Documentation

ctx

void* ra8_fs_backend_t::ctx

Caller-owned context passed back into the function pointers.

Definition at line 189 of file ra8_fs_types.h.

Referenced by internal_exfat_write_bitmap(), internal_exfat_write_fat(), internal_exfat_write_mbr(), internal_exfat_write_root(), internal_fmt_seed_fats(), internal_fmt_write_fsinfo(), internal_fmt_zero_run(), internal_mount_probe_bps(), internal_stub_probe(), lx_fs_backend_bind(), priv_exfat_write_upcase(), priv_fmt_clear_region(), priv_fmt_emit_volume(), priv_read_sector(), priv_write_sector(), ra8_io_blockdev_as_fs_backend(), and ra8_sdmmc_spi_bind_fs_backend().

erase_blocks

ra8_err_t(* ra8_fs_backend_t::erase_blocks) (void *ctx, uint64_t lba, uint64_t count)

OPTIONAL: bulk-erase count blocks at lba to all-zero bytes.

May be NULL. When non-NULL and it returns k_ra8_ok, the range [lba, lba+count) is guaranteed to read back as 0x00 – letting the formatter skip an explicit zero-write of that region (much faster on flash media that erases internally). A backend that cannot guarantee a zero post-erase value (or does not implement erase) must return k_ra8_err_not_supported so the formatter falls back to writing zeros; any other non-OK error aborts the format.

Parameters

[in]	ctx	Backend cookie.
[in]	lba	First block to erase.
[in]	count	Number of blocks to erase.

Definition at line 186 of file ra8_fs_types.h.

Referenced by lx_fs_backend_bind(), priv_fmt_clear_region(), ra8_io_blockdev_as_fs_backend(), and ra8_sdmmc_spi_bind_fs_backend().

get_capacity

ra8_err_t(* ra8_fs_backend_t::get_capacity) (void *ctx, uint64_t *block_count, uint32_t *block_size)

Report the device size.

Parameters

[out]	block_count	Total blocks (sectors).
[out]	block_size	Bytes per block: a power of two in k_ra8_fs_sector_min..k_ra8_fs_sector_max.

Definition at line 170 of file ra8_fs_types.h.

Referenced by internal_mount_probe_bps(), lx_fs_backend_bind(), ra8_io_blockdev_as_fs_backend(), and ra8_sdmmc_spi_bind_fs_backend().

read_block

ra8_err_t(* ra8_fs_backend_t::read_block) (void *ctx, uint64_t lba, uint32_t count, uint8_t *buf)

Read count consecutive blocks starting at lba.

Parameters

[in]	ctx	Backend cookie.
[in]	lba	Logical block address (0 = BPB).
[in]	count	Number of blocks to read.
[out]	buf	Destination buffer of at least count * block_size bytes.

Definition at line 157 of file ra8_fs_types.h.

Referenced by internal_stub_probe(), lx_fs_backend_bind(), priv_read_sector(), ra8_io_blockdev_as_fs_backend(), and ra8_sdmmc_spi_bind_fs_backend().

write_block

ra8_err_t(* ra8_fs_backend_t::write_block) (void *ctx, uint64_t lba, uint32_t count, const uint8_t *buf)

Write count consecutive blocks starting at lba.

Definition at line 162 of file ra8_fs_types.h.

Referenced by internal_exfat_write_bitmap(), internal_exfat_write_fat(), internal_exfat_write_mbr(), internal_exfat_write_root(), internal_fmt_seed_fats(), internal_fmt_write_fsinfo(), internal_fmt_zero_run(), lx_fs_backend_bind(), priv_exfat_write_upcase(), priv_fmt_emit_volume(), priv_write_sector(), ra8_io_blockdev_as_fs_backend(), and ra8_sdmmc_spi_bind_fs_backend().

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The documentation for this struct was generated from the following file:

• libs/ra8_fs/inc/ra8_fs_types.h