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// #################################################################################################
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// # << NEORV32: neorv32_cpu.h - CPU Core Functions HW Driver >> #
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// # ********************************************************************************************* #
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// # BSD 3-Clause License #
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// # #
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// # Copyright (c) 2020, Stephan Nolting. All rights reserved. #
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// # #
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// # Redistribution and use in source and binary forms, with or without modification, are #
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// # permitted provided that the following conditions are met: #
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// # #
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// # 1. Redistributions of source code must retain the above copyright notice, this list of #
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// # conditions and the following disclaimer. #
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// # #
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// # 2. Redistributions in binary form must reproduce the above copyright notice, this list of #
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// # conditions and the following disclaimer in the documentation and/or other materials #
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// # provided with the distribution. #
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// # #
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// # 3. Neither the name of the copyright holder nor the names of its contributors may be used to #
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// # endorse or promote products derived from this software without specific prior written #
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// # permission. #
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// # #
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// # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS #
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// # OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF #
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// # MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE #
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// # COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, #
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// # EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE #
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// # GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED #
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// # AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING #
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// # NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED #
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// # OF THE POSSIBILITY OF SUCH DAMAGE. #
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// # ********************************************************************************************* #
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// # The NEORV32 Processor - https://github.com/stnolting/neorv32 (c) Stephan Nolting #
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// #################################################################################################
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/**********************************************************************//**
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* @file neorv32_cpu.h
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* @author Stephan Nolting
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* @brief CPU Core Functions HW driver header file.
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**************************************************************************/
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#ifndef neorv32_cpu_h
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#define neorv32_cpu_h
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// prototypes
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int neorv32_cpu_irq_enable(uint8_t irq_sel);
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int neorv32_cpu_irq_disable(uint8_t irq_sel);
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void neorv32_cpu_delay_ms(uint32_t time_ms);
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/**********************************************************************//**
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* Read data from CPU configuration and status register (CSR).
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*
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* @param[in] csr_id ID of CSR to read. See #NEORV32_CPU_CSRS_enum.
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* @return Read data (uint32_t).
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**************************************************************************/
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inline uint32_t __attribute__ ((always_inline)) neorv32_cpu_csr_read(const int csr_id) {
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register uint32_t csr_data;
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asm volatile ("csrr %[result], %[input_i]" : [result] "=r" (csr_data) : [input_i] "i" (csr_id));
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return csr_data;
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}
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/**********************************************************************//**
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* Write data to CPU configuration and status register (CSR).
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*
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* @param[in] csr_id ID of CSR to write. See #NEORV32_CPU_CSRS_enum.
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* @param[in] data Data to write (uint32_t).
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**************************************************************************/
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inline void __attribute__ ((always_inline)) neorv32_cpu_csr_write(const int csr_id, uint32_t data) {
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register uint32_t csr_data = data;
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asm volatile ("csrw %[input_i], %[input_j]" : : [input_i] "i" (csr_id), [input_j] "r" (csr_data));
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}
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/**********************************************************************//**
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* Put CPU into "sleep" mode.
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*
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* @note This function executes the WFI insstruction.
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* The WFI (wait for interrupt) instruction will make the CPU stall until
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* an interupt request is detected. Interrupts have to be globally enabled
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* and at least one external source must be enabled (e.g., the CLIC or the machine
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* timer) to allow the CPU to wake up again. If 'Zicsr' CPU extension is disabled,
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* this will permanently stall the CPU.
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**************************************************************************/
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inline void __attribute__ ((always_inline)) neorv32_cpu_sleep(void) {
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asm volatile ("wfi");
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}
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/**********************************************************************//**
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* Enable global CPU interrupts (via MIE flag in mstatus CSR).
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**************************************************************************/
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inline void __attribute__ ((always_inline)) neorv32_cpu_eint(void) {
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asm volatile ("csrrsi zero, mstatus, %0" : : "i" (1 << CPU_MSTATUS_MIE));
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}
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/**********************************************************************//**
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* Disable global CPU interrupts (via MIE flag in mstatus CSR).
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**************************************************************************/
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inline void __attribute__ ((always_inline)) neorv32_cpu_dint(void) {
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asm volatile ("csrrci zero, mstatus, %0" : : "i" (1 << CPU_MSTATUS_MIE));
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}
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/**********************************************************************//**
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* Trigger machine software interrupt.
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*
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* @note The according IRQ has to be enabled via neorv32_cpu_irq_enable(uint8_t irq_sel) and
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* global interrupts must be enabled via neorv32_cpu_eint(void) to trigger an IRQ via software.
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* The MSI becomes active after 3 clock cycles.
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**************************************************************************/
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inline void __attribute__ ((always_inline)) neorv32_cpu_sw_irq(void) {
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asm volatile ("csrrsi zero, mip, %0" : : "i" (1 << CPU_MIP_MSIP));
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// the MSI becomes active 3 clock cycles afters issueing
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asm volatile ("nop"); // these nops are not required, they just make sure the MSI becomes active
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asm volatile ("nop"); // before the "real" next operation is executed
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}
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/**********************************************************************//**
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* Trigger breakpoint exception (via EBREAK instruction).
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**************************************************************************/
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inline void __attribute__ ((always_inline)) neorv32_cpu_breakpoint(void) {
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asm volatile ("ebreak");
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}
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/**********************************************************************//**
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* Trigger "environment call" exception (via ECALL instruction).
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**************************************************************************/
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inline void __attribute__ ((always_inline)) neorv32_cpu_env_call(void) {
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asm volatile ("ecall");
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}
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#endif // neorv32_cpu_h
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