Merge branch 'writing-os-in-1000-lines'

writing_os_in_1000_lines/.gitignore

@@ -0,0 +1,7 @@
+*.map
+*.tar
+*.o
+*.elf
+*.bin
+*.log
+*.pcap

writing_os_in_1000_lines/Makefile

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+CC := clang
+CFLAGS := -std=c11 -O2 -g3 -Wall -Wextra --target=riscv32 -ffreestanding -nostdlib
+OBJCOPY := llvm-objcopy
+FS := $(wildcard disk/*)
+
+all: kernel.elf shell.bin.o disk.tar opensbi-riscv32-generic-fw_dynamic.bin
+
+kernel.elf: kernel.ld kernel.c kernel.h common.c common.h shell.bin.o
+	$(CC) $(CFLAGS) -Wl,-Tkernel.ld -Wl,-Map=kernel.map -o kernel.elf \
+		kernel.c common.c shell.bin.o
+
+shell.elf: user.ld shell.c user.c user.h common.c common.h
+	$(CC) $(CFLAGS) -Wl,-Tuser.ld -Wl,-Map=shell.map -o shell.elf \
+		shell.c user.c common.c
+shell.bin: shell.elf
+	$(OBJCOPY) --set-section-flags .bss=alloc,contents -O binary shell.elf shell.bin
+shell.bin.o: shell.bin
+	$(OBJCOPY) -Ibinary -Oelf32-littleriscv shell.bin shell.bin.o
+
+disk.tar: $(FS)
+	(cd ./disk && tar cf ../disk.tar --format=ustar ./*.txt)
+
+opensbi-riscv32-generic-fw_dynamic.bin:
+	curl -LO https://github.com/qemu/qemu/raw/v8.0.4/pc-bios/opensbi-riscv32-generic-fw_dynamic.bin
+
+clean:
+	rm *.elf *.map *.bin *.o disk.tar
+
+.PHONY: clean all

writing_os_in_1000_lines/README.md

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+Writing OS in 1000 lines
+========================
+
+This is a very small toy OS written in about 1000 lines following the below guide.
+
+https://operating-system-in-1000-lines.vercel.app/ja/welcome
+
+```console
+$ tokei *.c *.h                                                                                                                                                                                                                                                                              [Husky.local][09/22 23:09]
+===============================================================================
+ Language            Files        Lines         Code     Comments       Blanks
+===============================================================================
+ C                       4          948          715          108          125
+ C Header                3          247          206           15           26
+===============================================================================
+ Total                   7         1195          921          123          151
+===============================================================================
+```
+
+### Repository structure
+
+```
+├── disk/     - Filesystem content
+├── common.c  - Common libraries shared by both kernel and (e.g. `printf`, `memset`)
+├── common.h  - Common libraries shared by both kernel and (structs and constants)
+├── kernel.c  - Kernel: Process management, system call, device driver, filesystem
+├── kernel.h  - Kernel: structs and constants
+├── kernel.ld - Kernel: Linker script (definition of memory layout)
+├── shell.c   - Command line shell
+├── user.c    - Libraries for user land: Functions for using system calls, ...
+├── user.h    - Libraries for user land: Structs and constants
+├── user.ld   - User land: Linker script (definition of memory layout)
+├── Makefile  - Build script
+└── run.sh    - Script to run kernel with QEMU
+```
+
+### How to build
+
+```sh
+source env.sh  # For macOS
+make
+```
+
+### How to run QEMU
+
+```sh
+./run.bash
+```

writing_os_in_1000_lines/common.c

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+#include "common.h"
+
+void putchar(char ch);
+
+void *memset(void *buf, char c, size_t n) {
+    uint8_t *p = (uint8_t *)buf;
+    while (n--) {
+        *p++ = c;
+    }
+    return buf;
+}
+
+void *memcpy(void *dst, void const *src, size_t n) {
+    uint8_t *d = (uint8_t *)dst;
+    uint8_t const *s = (uint8_t const *)src;
+    while (n--) {
+        *d++ = *s++;
+    }
+    return dst;
+}
+
+char *strcpy(char *dst, char const *src) {
+    char *d = dst;
+    while (*src) {
+        *d++ = *src++;
+    }
+    *d = '\0';
+    return dst;
+}
+
+int strcmp(char const *s1, char const *s2) {
+    while (*s1 && *s2 && *s1 == *s2) {
+        s1++;
+        s2++;
+    }
+    return *s1 - *s2;
+}
+
+int strlen(char const *s) {
+    for (int i = 0;; i++) {
+        if (s[i] == '\0') {
+            return i;
+        }
+    }
+}
+
+bool startswith(char const *heystack, char const *needle) {
+    for (int i = 0;; i++) {
+        char const h = heystack[i], n = needle[i];
+        if (n == '\0') {
+            return true;
+        }
+        if (h != n) {
+            return false;
+        }
+    }
+}
+
+void printf(char const *fmt, ...) {
+    va_list vargs;
+    va_start(vargs, fmt);
+
+    while (*fmt) {
+        if (*fmt == '%') {
+            if (*(fmt + 1)) {
+                fmt++;
+            }
+            switch (*fmt) {
+            case '%':
+                putchar('%');
+                break;
+            case 's': {
+                char const *s = va_arg(vargs, const char *);
+                while (*s) {
+                    putchar(*s);
+                    s++;
+                }
+                break;
+            }
+            case 'd': {
+                int value = va_arg(vargs, int);
+                if (value < 0) {
+                    putchar('-');
+                    value = -value;
+                }
+
+                int divisor = 1;
+                while (value / divisor > 9) {
+                    divisor *= 10;
+                }
+
+                while (divisor > 0) {
+                    putchar('0' + value / divisor);
+                    value %= divisor;
+                    divisor /= 10;
+                }
+
+                break;
+            }
+            case 'x': {
+                int value = va_arg(vargs, int);
+                for (int i = 7; i >= 0; i--) {
+                    int nibble = (value >> (i * 4)) & 0xf;
+                    putchar("0123456789abcdef"[nibble]);
+                }
+            }
+            }
+        } else {
+            putchar(*fmt);
+        }
+
+        fmt++;
+    }
+
+    va_end(vargs);
+}

writing_os_in_1000_lines/common.h

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+#pragma once
+
+typedef int bool;
+typedef unsigned char uint8_t;
+typedef unsigned short uint16_t;
+typedef unsigned int uint32_t;
+typedef unsigned long long uint64_t;
+typedef uint32_t size_t;
+typedef uint32_t paddr_t; // Physical address type
+typedef uint32_t vaddr_t; // Virtual address type
+
+#define true 1
+#define false 0
+#define NULL ((void *)0)
+#define align_up(value, align) __builtin_align_up(value, align) // Get next aligned value
+#define is_aligned(value, align) __builtin_is_aligned(value, align)
+#define offsetof(type, member) __builtin_offsetof(type, member) // Get struct member byte offset
+#define va_list __builtin_va_list
+#define va_start __builtin_va_start
+#define va_end __builtin_va_end
+#define va_arg __builtin_va_arg
+
+#define SYSCALL_PUTCHAR 1
+#define SYSCALL_GETCHAR 2
+#define SYSCALL_EXIT 3
+#define SYSCALL_READFILE 4
+#define SYSCALL_WRITEFILE 5
+
+void *memset(void *buf, char c, size_t n);
+void *memcpy(void *dst, void const *src, size_t n);
+char *strcpy(char *dst, char const *src);
+int strcmp(char const *s1, char const *s2);
+int strlen(char const *s);
+bool startswith(char const *heystack, char const *needle);
+void printf(char const *fmt, ...);

writing_os_in_1000_lines/disk/bowwow.txt

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+bow wow!

writing_os_in_1000_lines/disk/hello.txt

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+hello world from text file in the filesystem!

writing_os_in_1000_lines/env.sh

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+#!/bin/sh
+
+export PATH="/usr/local/opt/llvm/bin:$PATH"