Tool/software: TI C/C++ Compiler
Hello.
I've run into a problem where I'm trying to add two large numbers and I'm losing the carry bit when I increase the optimizer level to 2.
To demonstrate the problem I have lightly modified the uart loopback example (uart_loopback_24mhz_brclk.c). At none, 0 or 1 optimization it outputs a "y" for successful result.
At level 2 and above, I get a "n". The carry bit is not being carried between each 32bit addition.
Is this user error, or failure of the optimizer? I've tried a for() loop instead of while() and get the same result.
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IN NO EVENT SHALL THE COPYRIGHT OWNER OR * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, * EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. * --/COPYRIGHT--*/ /****************************************************************************** * MSP432 UART - Loopback with 24MHz DCO BRCLK * * Description: This demo connects TX to RX of the MSP432 UART * The example code shows proper initialization of registers * and interrupts to receive and transmit data. If data is incorrect P1.0 LED * is turned ON. * * MCLK = HSMCLK = SMCLK = DCO of 24MHz * * MSP432P401 * ----------------- * | | * RST -| P1.3/UCA0TXD|----| * | | | * -| | | * | P1.2/UCA0RXD|----| * | | * | P1.0|---> LED * | | * *******************************************************************************/ /* DriverLib Includes */ #include <ti/devices/msp432p4xx/driverlib/driverlib.h> /* Standard Includes */ #include <stdint.h> #include <stdbool.h> #include <stddef.h> uint8_t TXData = 1; uint8_t RXData = 0; /* UART Configuration Parameter. These are the configuration parameters to * make the eUSCI A UART module to operate with a 115200 baud rate. These * values were calculated using the online calculator that TI provides * at: * software-dl.ti.com/.../index.html */ const eUSCI_UART_Config uartConfig = { EUSCI_A_UART_CLOCKSOURCE_SMCLK, // SMCLK Clock Source 13, // BRDIV = 13 0, // UCxBRF = 0 37, // UCxBRS = 37 EUSCI_A_UART_NO_PARITY, // No Parity EUSCI_A_UART_MSB_FIRST, // MSB First EUSCI_A_UART_ONE_STOP_BIT, // One stop bit EUSCI_A_UART_MODE, // UART mode EUSCI_A_UART_OVERSAMPLING_BAUDRATE_GENERATION // Oversampling }; uint32_t BigAdd(uint32_t *result, const uint32_t *x, const uint32_t *y, size_t size) { uint64_t carry = 0; while (size > 0) { carry += *x++; carry += *y++; *result++ = (uint32_t)carry; carry >>= 32; --size; } return (uint32_t)carry; } const uint32_t one_256bit[8] = {0x00000001, 0x00000000, 0x00000000, 0x00000000, 0x00000000, 0x00000000, 0x00000000, 0x00000000 }; const uint32_t efs_256bit[8] = {0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF }; int main(void) { uint32_t result[8]; /* Halting WDT */ MAP_WDT_A_holdTimer(); /* Selecting P1.2 and P1.3 in UART mode and P1.0 as output (LED) */ MAP_GPIO_setAsPeripheralModuleFunctionInputPin(GPIO_PORT_P1, GPIO_PIN2 | GPIO_PIN3, GPIO_PRIMARY_MODULE_FUNCTION); MAP_GPIO_setAsOutputPin(GPIO_PORT_P1, GPIO_PIN0); MAP_GPIO_setOutputLowOnPin(GPIO_PORT_P1, GPIO_PIN0); /* Setting DCO to 24MHz (upping Vcore) */ FlashCtl_setWaitState(FLASH_BANK0, 1); FlashCtl_setWaitState(FLASH_BANK1, 1); MAP_PCM_setCoreVoltageLevel(PCM_VCORE1); CS_setDCOCenteredFrequency(CS_DCO_FREQUENCY_24); /* Configuring UART Module */ MAP_UART_initModule(EUSCI_A0_BASE, &uartConfig); /* Enable UART module */ MAP_UART_enableModule(EUSCI_A0_BASE); /* Enabling interrupts */ MAP_UART_enableInterrupt(EUSCI_A0_BASE, EUSCI_A_UART_RECEIVE_INTERRUPT); MAP_Interrupt_enableInterrupt(INT_EUSCIA0); MAP_Interrupt_enableSleepOnIsrExit(); if(BigAdd(result,one_256bit,efs_256bit,8)) MAP_UART_transmitData(EUSCI_A0_BASE, 'y'); else MAP_UART_transmitData(EUSCI_A0_BASE, 'n'); while(1) { MAP_UART_transmitData(EUSCI_A0_BASE, TXData); MAP_Interrupt_enableSleepOnIsrExit(); MAP_PCM_gotoLPM0InterruptSafe(); } } /* EUSCI A0 UART ISR - Echos data back to PC host */ void EUSCIA0_IRQHandler(void) { uint32_t status = MAP_UART_getEnabledInterruptStatus(EUSCI_A0_BASE); MAP_UART_clearInterruptFlag(EUSCI_A0_BASE, status); if(status & EUSCI_A_UART_RECEIVE_INTERRUPT_FLAG) { RXData = MAP_UART_receiveData(EUSCI_A0_BASE); if(RXData != TXData) // Check value { MAP_GPIO_setOutputHighOnPin(GPIO_PORT_P1, GPIO_PIN0); while(1); // Trap CPU } TXData++; MAP_Interrupt_disableSleepOnIsrExit(); } }
