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AP_IOMCU: optimisations to reduce ISR latency

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this speeds up the DMA ISR handlers to reduce the change of losing a
byte on RC input due to loss of an interrupt
This commit is contained in:
Andrew Tridgell 2018-11-26 21:46:22 +11:00
parent 24b23d6784
commit 69c4fb671e
2 changed files with 13 additions and 8 deletions
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19
libraries/AP_IOMCU/iofirmware/iofirmware.cpp
View File

@ -28,7 +28,10 @@
extern const AP_HAL::HAL &hal;
//#pragma GCC optimize("Og")
// we build this file with optimisation to lower the interrupt
// latency. This helps reduce the chance of losing an RC input byte
// due to missing a UART interrupt
#pragma GCC optimize("O3")
static AP_IOMCU_FW iomcu;
@ -335,10 +338,11 @@ void AP_IOMCU_FW::process_io_packet()
calc_crc = crc_crc8((const uint8_t *)&rx_io_packet, pkt_size);
}
if (rx_crc != calc_crc || rx_io_packet.count > PKT_MAX_REGS) {
memset(&tx_io_packet, 0xFF, sizeof(tx_io_packet));
tx_io_packet.count = 0;
tx_io_packet.code = CODE_CORRUPT;
tx_io_packet.crc = 0;
tx_io_packet.page = 0;
tx_io_packet.offset = 0;
tx_io_packet.crc = crc_crc8((const uint8_t *)&tx_io_packet, tx_io_packet.get_size());
stats.num_bad_crc++;
return;
@ -347,10 +351,11 @@ void AP_IOMCU_FW::process_io_packet()
case CODE_READ: {
stats.num_code_read++;
if (!handle_code_read()) {
memset(&tx_io_packet, 0xFF, sizeof(tx_io_packet));
tx_io_packet.count = 0;
tx_io_packet.code = CODE_ERROR;
tx_io_packet.crc = 0;
tx_io_packet.page = 0;
tx_io_packet.offset = 0;
tx_io_packet.crc = crc_crc8((const uint8_t *)&tx_io_packet, tx_io_packet.get_size());
}
}
@ -358,10 +363,11 @@ void AP_IOMCU_FW::process_io_packet()
case CODE_WRITE: {
stats.num_write_pkt++;
if (!handle_code_write()) {
memset(&tx_io_packet, 0xFF, sizeof(tx_io_packet));
tx_io_packet.count = 0;
tx_io_packet.code = CODE_ERROR;
tx_io_packet.crc = 0;
tx_io_packet.page = 0;
tx_io_packet.offset = 0;
tx_io_packet.crc = crc_crc8((const uint8_t *)&tx_io_packet, tx_io_packet.get_size());
}
}
@ -371,8 +377,6 @@ void AP_IOMCU_FW::process_io_packet()
}
break;
}
rx_io_last = rx_io_packet;
memset((void *)&rx_io_packet, 0x42, sizeof(rx_io_packet));
}
/*
@ -596,10 +600,11 @@ bool AP_IOMCU_FW::handle_code_write()
default:
break;
}
memset(&tx_io_packet, 0xFF, sizeof(tx_io_packet));
tx_io_packet.count = 0;
tx_io_packet.code = CODE_SUCCESS;
tx_io_packet.crc = 0;
tx_io_packet.page = 0;
tx_io_packet.offset = 0;
tx_io_packet.crc = crc_crc8((const uint8_t *)&tx_io_packet, tx_io_packet.get_size());
return true;
}

2
libraries/AP_IOMCU/iofirmware/iofirmware.h
View File

@ -12,7 +12,7 @@ class AP_IOMCU_FW {
public:
void process_io_packet();
struct IOPacket rx_io_packet, tx_io_packet, rx_io_last;
struct IOPacket rx_io_packet, tx_io_packet;
void init();
void update();