big_buffer.cpp

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#include "pch.h"
 
#include "big_buffer.h"
 
static BigBufferUser s_currentUser;
// uint32_t type to get 4-byte alignment
// alignment is required since we sometimes allocate objects in the buffer (like Timer of CompositeBuffer)
// we've only observed issue on F7 in -Os compiler configuration but technically all processors care
static uint32_t s_bigBuffer[BIG_BUFFER_SIZE / sizeof(uint32_t)];
 
#if EFI_UNIT_TEST
BigBufferUser getBigBufferCurrentUser() {
  return s_currentUser;
}
#endif // EFI_UNIT_TEST
 
static void releaseBuffer(void* bufferPtr, BigBufferUser user) {
    if (bufferPtr != &s_bigBuffer || user != s_currentUser) {
        // todo: panic!
    }
 
    s_currentUser = BigBufferUser::None;
}
 
BigBufferHandle::BigBufferHandle(void* buffer, BigBufferUser user)
    : m_bufferPtr(buffer)
    , m_user(user)
{
}
 
BigBufferHandle::BigBufferHandle(BigBufferHandle&& other) {
    // swap contents of the two objects
    m_bufferPtr = other.m_bufferPtr;
    other.m_bufferPtr = nullptr;
 
    m_user = other.m_user;
    other.m_user = BigBufferUser::None;
}
 
BigBufferHandle& BigBufferHandle::operator= (BigBufferHandle&& other) {
    if (this != &other) {
        if (m_bufferPtr) {
            releaseBuffer(m_bufferPtr, m_user);
        }
        // swap contents of the two objects
        m_bufferPtr = other.m_bufferPtr;
        other.m_bufferPtr = nullptr;
 
        m_user = other.m_user;
        other.m_user = BigBufferUser::None;
    }
    return *this;
}
 
BigBufferHandle::~BigBufferHandle() {
    if (m_bufferPtr) {
        releaseBuffer(m_bufferPtr, m_user);
    }
}
 
BigBufferHandle getBigBuffer(BigBufferUser user) {
    if (s_currentUser != BigBufferUser::None) {
        // fatal
        return {};
    }
 
    s_currentUser = user;
 
    return BigBufferHandle(s_bigBuffer, user);
}