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41 lines
1.1 KiB
C
41 lines
1.1 KiB
C
//===----------------------------------------------------------------------===//
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//
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// This source file is part of the Swift open source project
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//
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// Copyright (c) 2024 Apple Inc. and the Swift project authors.
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// Licensed under Apache License v2.0 with Runtime Library Exception
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//
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// See https://swift.org/LICENSE.txt for license information
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// See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
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//
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//===----------------------------------------------------------------------===//
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#include <stddef.h>
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#include <stdint.h>
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int puts(const char *p);
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__attribute__((naked))
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__attribute__((section(".start")))
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void start() {
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asm volatile("la sp, stack + 8192 - 4");
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asm volatile("call main");
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asm volatile("call halt");
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}
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void halt(void) {
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puts("HALT\n");
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asm("unimp");
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}
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__attribute__((aligned(4))) char stack[8192];
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int putchar(int c) {
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// This is only valid in an emulator (QEMU), and it's skipping a proper configuration of the UART device
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// and waiting for a "ready to transit" state.
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// QEMU riscv32-virt's specific location of the 16550A UART and its THR register
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*(volatile uint8_t *)(0x10000000 + 0) = c;
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return c;
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}
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