sbl::hal::interrupts Namespace Reference

Interrupt priorities and critical sections. More...

Detailed Description

Interrupt priorities and critical sections.

Classes
class	ScopedControlCritical
	RAII critical section against the control tick and everything below. More...

Enumerations
enum class	Level : uint8_t {   Reserved = 0 , ShortDeadline = 1 , Audio = 2 , UsbMidi = 4 ,   Dma = 5 , Bus = 6 , ControlTick = 8 , SoftPwm = 9 ,   Exti = 10 , SoftPend = 11 , Debug = 12 , SysTick = 14 ,   PendSv = 15 }
	Execution levels, most urgent first. More...
enum class	Trigger : uint8_t {   Rising , Falling , Change , Low ,   High }
	External interrupt trigger types. More...

Functions
uint32_t	get_basepri ()
	Read BASEPRI (0 = no ceiling).
void	set_basepri (uint32_t encoded)
	Write BASEPRI unconditionally (used to restore a saved value).
void	raise_basepri (uint32_t encoded)
uint32_t	disable_and_save ()
	Disable all configurable exceptions and return the previous PRIMASK.
void	restore (uint32_t saved_state)
	Restore PRIMASK from disable_and_save().
uint32_t	get_state ()
	Current PRIMASK (0 = enabled, 1 = disabled).
bool	are_enabled ()
	True if configurable exceptions are enabled (PRIMASK clear).
constexpr uint8_t	encode (Level level)
	Encode a level as the byte written to NVIC->IP[] / SCB->SHP[] / BASEPRI.
constexpr bool	masked_by_ceiling (Level level)
	True if a handler at level is masked while BASEPRI sits at the ceiling.

Variables
constexpr Level	kBasepriCeiling = Level::ControlTick
	The level a ScopedControlCritical raises BASEPRI to.
constexpr uint8_t	kPriorityBits = 4
	Priority bits the target implements (STM32H750: 4 of 8).

Enumeration Type Documentation

Level

enum class sbl::hal::interrupts::Level : uint8_t

strong

Execution levels, most urgent first.

The invariants the scheme guarantees:

• Level 0 stays empty, so nothing can ever tie with audio and nothing escapes BASEPRI.
• Audio has its own level. Any handler that shares it would delay audio by its full length (equal priority cannot preempt).
• ControlTick is the BASEPRI ceiling: a ScopedControlCritical masks this level and everything below it, and nothing above it may touch state that main or the tick protect. Audio's blocking term is therefore zero.
• SysTick, PendSV and SVCall are assigned explicitly; unassigned system handlers reset to level 0, above audio.

Enumerator
Reserved	Empty by design (unmaskable by BASEPRI)
ShortDeadline	Reserved for microsecond handlers that touch only SPSC queues.
Audio	Audio DMA half/complete — the SAI streams only.
UsbMidi	USB OTG interrupt, MIDI UART RX (both FIFO-elastic)
Dma	Every other DMA stream (ADC, SDMMC)
Bus	I2C / SPI event handlers, if interrupt-driven.
ControlTick	Control-rate timer tick — the BASEPRI ceiling.
SoftPwm	Software PWM / BCM timer (tolerates tick preemption)
Exti	External pin interrupts (encoders, buttons)
SoftPend	Software-pended work: tud_task(), USB-MIDI parse.
Debug	Debug UART, diagnostics drain.
SysTick	Millisecond tick; busy_wait_ms works from any level below.
PendSv	PendSV and SVCall (left free for an RTOS later)

Definition at line 39 of file types.hpp.

Trigger

enum class sbl::hal::interrupts::Trigger : uint8_t

strong

External interrupt trigger types.

Enumerator
Rising	Rising edge trigger.
Falling	Falling edge trigger.
Change	Any edge (rising or falling)
Low	Low level trigger.
High	High level trigger.

Definition at line 74 of file types.hpp.

Function Documentation

get_basepri()

uint32_t sbl::hal::interrupts::get_basepri ( )

inline

Read BASEPRI (0 = no ceiling).

Definition at line 48 of file control.hpp.

set_basepri()

void sbl::hal::interrupts::set_basepri ( uint32_t  encoded )

inline

Write BASEPRI unconditionally (used to restore a saved value).

Definition at line 59 of file control.hpp.

Referenced by sbl::hal::interrupts::ScopedControlCritical::~ScopedControlCritical().

raise_basepri()

void sbl::hal::interrupts::raise_basepri ( uint32_t  encoded )

inline

Raise BASEPRI to encoded only if that is a higher priority than the current value — never lowers it, so nested sections compose.

Definition at line 69 of file control.hpp.

Referenced by sbl::hal::interrupts::ScopedControlCritical::ScopedControlCritical().

disable_and_save()

uint32_t sbl::hal::interrupts::disable_and_save ( )

inline

Disable all configurable exceptions and return the previous PRIMASK.

This blocks the audio ISR. It exists for assert/fault handling, where the system is already lost; a critical section wants ScopedControlCritical.

Definition at line 111 of file control.hpp.

restore()

void sbl::hal::interrupts::restore ( uint32_t  saved_state )

inline

Restore PRIMASK from disable_and_save().

Definition at line 123 of file control.hpp.

get_state()

uint32_t sbl::hal::interrupts::get_state ( )

inline

Current PRIMASK (0 = enabled, 1 = disabled).

Definition at line 132 of file control.hpp.

Referenced by are_enabled().

are_enabled()

bool sbl::hal::interrupts::are_enabled ( )

inline

True if configurable exceptions are enabled (PRIMASK clear).

Definition at line 143 of file control.hpp.

References get_state().

encode()

constexpr uint8_t sbl::hal::interrupts::encode ( Level  level )

constexpr

Encode a level as the byte written to NVIC->IP[] / SCB->SHP[] / BASEPRI.

Definition at line 62 of file types.hpp.

References kPriorityBits.

Referenced by sbl::hal::interrupts::ScopedControlCritical::ScopedControlCritical().

masked_by_ceiling()

constexpr bool sbl::hal::interrupts::masked_by_ceiling ( Level  level )

constexpr

True if a handler at level is masked while BASEPRI sits at the ceiling.

Definition at line 67 of file types.hpp.

References kBasepriCeiling.

Variable Documentation

kBasepriCeiling

constexpr Level sbl::hal::interrupts::kBasepriCeiling = Level::ControlTick

inlineconstexpr

The level a ScopedControlCritical raises BASEPRI to.

Definition at line 56 of file types.hpp.

Referenced by masked_by_ceiling(), and sbl::hal::interrupts::ScopedControlCritical::ScopedControlCritical().

kPriorityBits

constexpr uint8_t sbl::hal::interrupts::kPriorityBits = 4

inlineconstexpr

Priority bits the target implements (STM32H750: 4 of 8).

Definition at line 59 of file types.hpp.

Referenced by encode().