General Library on XWOS

Bit Operation Library

Mon, 01 Jan 0001 00:00:00 +0000

Bit Operations

XWOS provides a bit operation template library. Various non-function-pointer types defined in Basic Types can use bit operations. The bit operation function templates include:

xwbop_s1m(): Set all bits in the data mask portion to 1
xwbop_c0m(): Clear all bits in the data mask portion to 0
xwbop_x1m(): Toggle all bits in the data mask portion
xwbop_rbit(): Mirror-reverse the bits of the data
xwbop_re(): Reverse the endianness of the data
xwbop_ffs(): Find the first bit set to 1 starting from the least significant bit
xwbop_fls(): Find the first bit set to 1 starting from the most significant bit
xwbop_ffz(): Find the first bit cleared to 0 starting from the least significant bit
xwbop_flz(): Find the first bit cleared to 0 starting from the most significant bit
xwbop_weight(): Count the number of 1 bits in the data

The first parameter of all bit operation functions is the Basic Type, and the second parameter is the data or pointer to the data, for example:

Atomic Operation Library

Mon, 01 Jan 0001 00:00:00 +0000

Memory Model

Like the standard library, XWOS atomic operations are divided into 6 memory ordering models:

`xwaop_mo_relaxed`

Relaxed ordering, no memory barrier operations.

`xwaop_mo_consume`

Consume ordering, adds a Data dependency barrier between read operations. This barrier is uncommon; for common x86/ARM architectures, Data dependency barrier is handled automatically. To the author’s knowledge, currently only Alpha architecture CPUs require programmer attention to Data dependency barrier. The Rust language does not even provide this memory ordering.

Logging

Mon, 01 Jan 0001 00:00:00 +0000

Overview

XWOS provides a logging framework where users can output logs with levels:

VERBOSE, Level 1, verbose
DEBUG, Level 2, debug
INFO, Level 3, informational
NOTICE, Level 4, notice
WARNING, Level 5, warning
ERR, Level 6, error
CRIT, Level 7, critical
EMERG, Level 8, emergency

Users can control whether logs of various levels are output by configuring XWLIBCFG_XWLOG_LEVEL:

Only logs with a level greater than or equal to XWLIBCFG_XWLOG_LEVEL will be output.
When XWLIBCFG_XWLOG_LEVEL is configured as 0, all logs are disabled.

The XWOS logging framework requires the user to provide a backend driver interface in the BSP to determine whether logs are ultimately output to a serial port, SD card, or other device:

CRC

Mon, 01 Jan 0001 00:00:00 +0000

API Reference

CRC8
- Header file <xwos/lib/crc8.h>
CRC32
- Header file <xwos/lib/crc32.h>