psyqo::ScratchpadStackful< StackSize > Class Template Reference

Stackful coroutine whose stack is the scratchpad. More...

#include <psyqo/coroutine.hh>

Inheritance diagram for psyqo::ScratchpadStackful< StackSize >:

Collaboration diagram for psyqo::ScratchpadStackful< StackSize >:

Public Member Functions
	ScratchpadStackful ()=default
	ScratchpadStackful (const ScratchpadStackful &)=delete
ScratchpadStackful &	operator= (const ScratchpadStackful &)=delete
void	initialize (eastl::function< void()> &&func)
	Initialize the coroutine with a function.
void	resume ()
	Resume the coroutine. See Stackful::resume.
void	yield ()
	Yield the coroutine. See Stackful::yield.
bool	isAlive () const
	Check if the coroutine is currently alive. See Stackful::isAlive.

Static Public Attributes
static constexpr uintptr_t	c_stackBase = 0x1f800400 - StackSize
static constexpr unsigned	c_stackSize = StackSize
static constexpr unsigned	c_freeBytes = 1024 - StackSize

Additional Inherited Members
Protected Member Functions inherited from psyqo::StackfulBase
void	initializeInternal (eastl::function< void()> &&func, void *ss_sp, unsigned ss_size)
void	resume ()
void	yield ()
bool	isAlive () const
	StackfulBase ()=default
	StackfulBase (const StackfulBase &)=delete
StackfulBase &	operator= (const StackfulBase &)=delete

Detailed Description

template<unsigned StackSize = 1024>
class psyqo::ScratchpadStackful< StackSize >

Stackful coroutine whose stack is the scratchpad.

Same as Stackful, except that the stack is not part of the object: it is the top StackSize bytes of the 1KB scratchpad, growing down from 0x1f800400. The scratchpad answers a load in one cycle where main RAM takes several, so a hot routine that spends its time saving and restoring registers and reloading spilled locals gets faster by running here. The scratchpad-stack example measures it.

The constraints all come from the scratchpad itself:

• Only one can be alive at a time, since every instance uses the same bytes. Let one return before initializing the next.
• DMA cannot reach the scratchpad, so a local of the coroutine cannot be a DMA source or target. That includes a primitive or fragment built on its stack and then chained to the GPU.
• The bottom c_freeBytes bytes are left for data, such as variables placed with __attribute__((section(".scratchpad"))), which the linker allocates from 0x1f800000 upward. initialize aborts if the linked .scratchpad section, which ends at __scratchpad_end, reaches into the stack. A stack that overflows at run time still writes over that data silently.
• Only the main link's .scratchpad section is checked: data an overlay module places in the scratchpad is not accounted for.
• Interrupts do not run on this stack: psyqo's exception handler saves the registers it needs to fixed addresses and switches to its own stack before calling into C++.

Template Parameters

StackSize

The number of bytes taken from the top of the scratchpad. A multiple of 8, at most 1024.

Constructor & Destructor Documentation

ScratchpadStackful() [1/2]

template<unsigned StackSize = 1024>

psyqo::ScratchpadStackful< StackSize >::ScratchpadStackful ( )

default

ScratchpadStackful() [2/2]

template<unsigned StackSize = 1024>

psyqo::ScratchpadStackful< StackSize >::ScratchpadStackful ( const ScratchpadStackful< StackSize > &  )

delete

Member Function Documentation

initialize()

template<unsigned StackSize = 1024>

void psyqo::ScratchpadStackful< StackSize >::initialize ( eastl::function< void()> &&  func )

inline

Initialize the coroutine with a function.

Parameters

func	Function to be executed by the coroutine.

isAlive()

template<unsigned StackSize = 1024>

bool psyqo::ScratchpadStackful< StackSize >::isAlive ( ) const

inline

Check if the coroutine is currently alive. See Stackful::isAlive.

operator=()

template<unsigned StackSize = 1024>

ScratchpadStackful & psyqo::ScratchpadStackful< StackSize >::operator= ( const ScratchpadStackful< StackSize > &  )

delete

resume()

template<unsigned StackSize = 1024>

void psyqo::ScratchpadStackful< StackSize >::resume ( )

inline

Resume the coroutine. See Stackful::resume.

yield()

template<unsigned StackSize = 1024>

void psyqo::ScratchpadStackful< StackSize >::yield ( )

inline

Yield the coroutine. See Stackful::yield.

Member Data Documentation

c_freeBytes

template<unsigned StackSize = 1024>

constexpr unsigned psyqo::ScratchpadStackful< StackSize >::c_freeBytes = 1024 - StackSize

staticconstexpr

c_stackBase

template<unsigned StackSize = 1024>

constexpr uintptr_t psyqo::ScratchpadStackful< StackSize >::c_stackBase = 0x1f800400 - StackSize

staticconstexpr

c_stackSize

template<unsigned StackSize = 1024>

constexpr unsigned psyqo::ScratchpadStackful< StackSize >::c_stackSize = StackSize

staticconstexpr

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

• psyqo/coroutine.hh