make a file-operations of text VGA mode

LINES

@@ -24,3 +24,5 @@
 
 2021-2-25 0.790: 790 lines, 10 files, rain
 
+2021-3-12 1.384: 1384 lines, 20 files, rain
+

Makefile

@@ -5,11 +5,14 @@ all:
 	make cunix.img
 
 clear:
-	rm *.bin boot/x86/*.bin kernel/*.o kernel/*.bin kernel/init/*.o kernel/hal/*.o cunix.img -rf
+	make -C kernel/ clear
+	make -C boot/x86/ clear
+	rm cunix.img boot.bin
+
 
 
 lines:
-	wc boot/x86/boot.asm boot/x86/loader.asm kernel/init/*.c kernel/hal/*.c include/arch/x86/* include/kernel/* -l
+	wc boot/x86/boot.asm boot/x86/loader.asm kernel/init/*.c kernel/lib/*.c kernel/hal/vgatext/*.c include/arch/x86/* include/arch/*.h include/kernel/* include/lib/* -l
 
 
 cunix.img: boot/x86/bootloader.bin kernel/kernel.bin

README.md

@@ -9,7 +9,7 @@ Cunix kernel
 &nbsp;&nbsp;&nbsp;&nbsp;it uses `2MB` page to make 0-12 MB memory to `0x0000 - 0xc0000`. <br/>
 
 
-`0.385s-boot`: 
+`0.385s-boot`:  
 &nbsp;&nbsp;&nbsp;&nbsp;rebuild `boot` and `loader`. <br/>
 
 
@@ -36,21 +36,25 @@ Cunix kernel
 &nbsp;&nbsp;&nbsp;&nbsp;protect-mode. <br/>
 
 
-`0.484s-boot`:
+`0.484s-boot`:  
 &nbsp;&nbsp;&nbsp;&nbsp;let `readdisk.inc` smaller, but we just can use CHS or LBA, not both. <br/>
 
 
-`0.509s-kernel`: 
+`0.509s-kernel`:   
 &nbsp;&nbsp;&nbsp;&nbsp;load kernel to 0x8200-0x9200 for 4KB, kernel.asm display 'K' to screen. <br/>
 
-`0.556s-int`: 
+`0.556s-int`:  
 &nbsp;&nbsp;&nbsp;&nbsp;init IDT at 0x0000-0x1000, and set all handler at `ignore_int`, but it do nothing. <br/>
 
-`0.619s-boot`: 
+`0.619s-boot`:  
 &nbsp;&nbsp;&nbsp;&nbsp;load 180KB of disk, not 4KB <br/>
 
-`0.566s-kernel`:
+`0.566s-kernel`:  
 &nbsp;&nbsp;&nbsp;&nbsp;write in C. <br/>
 
-`0.790s-kernel`:
+`0.790s-kernel`:  
 &nbsp;&nbsp;&nbsp;&nbsp;make some structs <br/>
+
+`1.384s-hal`:  
+&nbsp;&nbsp;&nbsp;&nbsp;use text VGA mode, and make a file-operations of it. 
+

boot/x86/Makefile

@@ -18,3 +18,4 @@ bootloader.bin: boot.bin loader.bin
 
 clear:
 	rm *.bin 
+

boot/x86/loader.asm

@@ -28,8 +28,6 @@ jmp _start
 bits 16
 
 _start:	
-	call set_vga_mode
-
 	; enable A20 address 20 line
 .open_a20:
 	in al, 0x92
@@ -65,12 +63,6 @@ print:
 .do_ret:
 	ret
 
-set_vga_mode:
-	mov al, 0x13
-	mov ah, 0x00
-	int 0x10
-
-	ret
 
 bits 32
 

include/arch/io.h

+/* Copyright (C) 2021 Rain */
+
+/* This file is part of Cunix. */
+
+/* 
+  Cunix is free software: you can redistribute it and/or modify 
+  it under the terms of the GNU General Public License as published by 
+  the Free Software Foundation, either version 3 of the License, or 
+  (at your option) and later version. 
+*/
+
+/*
+  Cunix is distributed in the hope that it will be useful, 
+  but WITHOUT ANY WARRANTY; without even the implied warranty of 
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 
+  GNU General Public License for more details. 
+*/
+
+/*
+  You should have received a copy of the GNU General Public License 
+   along with Cunix. If not, see <https://www.gnu.org/licenses/>.  
+*/
+
+
+
+#ifndef INCLUDED_IO_H
+#define INCLUDED_IO_H
+
+#include <kernel/types.h>
+
+
+typedef __uint16_t port_t;
+
+
+#define inb(port) ({ \
+	__uint8_t _r; \
+	__asm__ volatile ("inb %%dx, %%al" : "=a" (_r) : "d" (port)); \
+	_r; \
+})
+
+#define inw(port) ({ \
+	__uint16_t _r; \
+	__asm__ volatile ("inw %%dx, %%ax" : "=a" (_r) : "d" (port)); \
+	_r; \
+})
+
+#define inl(port) ({ \
+	__uint32_t _r; \
+	__asm__ volatile ("inl %%dx, %%eax" : "=a" (_r) : "d" (port)); \
+	_r; \
+})
+
+
+#define outb(value, port) \
+	__asm__ volatile ("outb %%al, %%dx" :: "a" (value), "d" (port));
+
+#define outw(value, port) \
+	__asm__ volatile ("outw %%ax, %%dx" :: "a" (value), "d" (port));
+
+#define outl(value, port) \
+	__asm__ volatile ("outl %%eax, %%dx" :: "a" (value), "d" (port));
+
+
+#endif

include/kernel/errno.h

@@ -24,6 +24,9 @@
 
 
 
+#ifndef INCLUDED_ERRNO_H
+#define INCLUDED_ERRNO_H
+
 typedef __uint32_t errno_t;
 
 
@@ -31,36 +34,45 @@ typedef __uint32_t errno_t;
 #define E_KERROR 0x20000000
 
 /* error io port */
-#define E_IOERROR 0x00000001
+#define E_IOERROR 0x00000001 | E_KERROR
 
 /* no enough memory for this call */
-#define E_NOMEM	  0x00000002
+#define E_NOMEM	  0x00000002 | E_KERROR
 
 /* call interrupted by signal */
-#define E_SIGNAL  0x00000003
+#define E_SIGNAL  0x00000003 | E_KERROR
+
+/* kernel not supported */
+#define E_NOSUPP  0x00000004 | E_KERROR
 
 
 /* no permision */
 #define E_DENIED 0x40000000
 
 /* need root to call this */
-#define E_NDROOT 0x00000001
+#define E_NDROOT 0x00000001 | E_DENIED
 
 /* no io passport */
-#define E_IODND  0x00000002
+#define E_IODND  0x00000002 | E_DENIED
 
 /* need hardware super 0 */
-#define E_HARDSP 0x00000003
+#define E_HARDSP 0x00000003 | E_DENIED
+
+/* hardware no support */
+#define E_HNOSUP 0x00000004 | E_DENIED
 
 /* user error (caller) */
-#define E_UERROR 0x80000000
+#define E_UERROR 0x80000000 | E_UERROR
+
 
 /* syntax error for this call (invalid argument) */
-#define E_SYNERR 0x00000001
+#define E_SYNERR 0x00000001 | E_UERROR
 
 /* error because address is invalid */
-#define E_ADDRE  0x00000002
+#define E_ADDRE  0x00000002 | E_UERROR
 
 /* call out of range */
-#define E_OUTRAG 0x000000003
+#define E_OUTRAG 0x00000003 | E_UERROR
+
+#endif
 

include/kernel/init.h

@@ -24,19 +24,13 @@
 
 
 
-#include <kernel/types.h>
-#include <kernel/errno.h>
+#ifndef INCLUDED_INIT_H
+#define INCLUDED_INIT_H
 
 
+#include <kernel/types.h>
+#include <kernel/errno.h>
 
-#define MAKE_MODULE(name) struct file_operations name##_fop = { \
-	.open = name##_open; \
-	.creat = name##_create; \
-	.read = name##_read; \
-	.write = name##_write; \
-	.lseek = name##_lseek; \
-	.close = name##_close; \
-};
 
 
 struct inode_desc {
@@ -48,7 +42,7 @@ struct inode_desc {
 	/* file descriptor */
 	__uint32_t fd;
 
-	/* this is optional */
+	/* this is optional (offset) */
 	__uint32_t off;
 
 	/* this is optional too */
@@ -56,16 +50,18 @@ struct inode_desc {
 };
 
 
-struct file_oprerations {
+struct file_operations {
 	/* open a file */
 	struct inode_desc * (* open) (char *name, __uint32_t type, __uint32_t mode, __uint32_t *errno);
-	struct inode_desc * (* open) (__uint32_t type, __uint32_t mode, __uint32_t *errno);
 
 	/* or create one */
 
 	/* `creat` doesn't return file-descriptor, it returns errno */
 	errno_t (* creat) (char *name, __uint32_t type, __uint32_t mode);
-	errno_t (* creat) (__uint32_t type, __uint32_t mode);
+
+	/* `fill` fills a inode descriptor */
+	errno_t (* fill) (char *name, __uint32_t type, __uint32_t mode, struct inode_desc *i);
+
 
 	/* read from file-descriptor */
 	errno_t (* read) (struct inode_desc *i, char *buffer, __uint64_t l);
@@ -76,6 +72,11 @@ struct file_oprerations {
 	/* change position */
 
 	/* 'seg' = whence */
+
+#define SEEK_SET 0x0001
+#define SEEK_CUR 0x0002
+#define SEEK_END 0x0003
+
 	__uint32_t (* lseek) (struct inode_desc *i, __uint32_t off, __uint32_t seg);
 
 	/* close a file-descriptor */
@@ -83,3 +84,5 @@ struct file_oprerations {
 };
 
 
+#endif
+

include/kernel/module.h

+/* Copyright (C) 2021 Rain */
+
+/* This file is part of Cunix. */
+
+/* 
+  Cunix is free software: you can redistribute it and/or modify 
+  it under the terms of the GNU General Public License as published by 
+  the Free Software Foundation, either version 3 of the License, or 
+  (at your option) and later version. 
+*/
+
+/*
+  Cunix is distributed in the hope that it will be useful, 
+  but WITHOUT ANY WARRANTY; without even the implied warranty of 
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 
+  GNU General Public License for more details. 
+*/
+
+/*
+  You should have received a copy of the GNU General Public License 
+   along with Cunix. If not, see <https://www.gnu.org/licenses/>.  
+*/
+
+
+
+
+#ifndef INCLUDED_MODULE_H
+#define INCLUDED_MODULE_H
+
+#include <kernel/init.h>
+#include <kernel/types.h>
+#include <kernel/errno.h>
+
+
+#define INIT_MODULE(modn) { \
+	.open = modn##_open, \
+	.creat = modn##_creat, \
+	.fill = modn##_fill, \
+	.read = modn##_read, \
+	.write = modn##_write, \
+	.lseek = modn##_lseek, \
+	.close = modn##_close \
+};
+
+
+#endif

include/kernel/print.h

+/* Copyright (C) 2021 Rain */
+
+/* This file is part of Cunix. */
+
+/* 
+  Cunix is free software: you can redistribute it and/or modify 
+  it under the terms of the GNU General Public License as published by 
+  the Free Software Foundation, either version 3 of the License, or 
+  (at your option) and later version. 
+*/
+
+/*
+  Cunix is distributed in the hope that it will be useful, 
+  but WITHOUT ANY WARRANTY; without even the implied warranty of 
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 
+  GNU General Public License for more details. 
+*/
+
+/*
+  You should have received a copy of the GNU General Public License 
+   along with Cunix. If not, see <https://www.gnu.org/licenses/>.  
+*/
+
+
+
+
+#ifndef INCLUDED_PRINT_H
+#define INCLUDED_PRINT_H
+
+
+#include <kernel/types.h>
+#include <kernel/errno.h>
+
+#include <kernel/vgatext.h>
+
+__uint32_t print(struct vga_inode *inode, char *s);
+
+#endif
+

include/kernel/types.h

@@ -24,6 +24,9 @@
 
 
 
+#ifndef INCLUDED_TYPES_H
+#define INCLUDED_TYPES_H
+
 #define NULL (void *) 0
 
 
@@ -45,3 +48,5 @@ typedef __uint_t 	__uint32_t;
 typedef __ulong_t 	__uint64_t;
 
 
+#endif
+

include/kernel/vgatext.h

+/* Copyright (C) 2021 Rain */
+
+/* This file is part of Cunix. */
+
+/* 
+  Cunix is free software: you can redistribute it and/or modify 
+  it under the terms of the GNU General Public License as published by 
+  the Free Software Foundation, either version 3 of the License, or 
+  (at your option) and later version. 
+*/
+
+/*
+  Cunix is distributed in the hope that it will be useful, 
+  but WITHOUT ANY WARRANTY; without even the implied warranty of 
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 
+  GNU General Public License for more details. 
+*/
+
+/*
+  You should have received a copy of the GNU General Public License 
+   along with Cunix. If not, see <https://www.gnu.org/licenses/>.  
+*/
+
+
+
+
+#ifndef INCLUDED_VGA_H
+#define INCLUDED_VGA_H
+
+
+#include <kernel/init.h>
+#include <kernel/errno.h>
+#include <kernel/types.h>
+#include <kernel/module.h>
+
+
+#define TEXT_VGA_X 80
+
+
+
+extern struct file_operations vga;
+
+struct vga_inode {
+	struct inode_desc inode;
+
+	/* frame buffer start address */
+	/* frame buffer in text mode: 
+	   char ASCII | char COLOR
+	*/
+
+	/* but use char is easier */
+
+	__uint8_t *fb;
+
+	__uint32_t x, y;
+};
+
+#endif
+

include/lib/bitman.h

+/* Copyright (C) 2021 Rain */
+
+/* This file is part of Cunix. */
+
+/* 
+  Cunix is free software: you can redistribute it and/or modify 
+  it under the terms of the GNU General Public License as published by 
+  the Free Software Foundation, either version 3 of the License, or 
+  (at your option) and later version. 
+*/
+
+/*
+  Cunix is distributed in the hope that it will be useful, 
+  but WITHOUT ANY WARRANTY; without even the implied warranty of 
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 
+  GNU General Public License for more details. 
+*/
+
+/*
+  You should have received a copy of the GNU General Public License 
+   along with Cunix. If not, see <https://www.gnu.org/licenses/>.  
+*/
+
+
+
+
+struct bitmap_manager {
+	unsigned char *bitmap;
+	unsigned int next_free;
+};
+
+unsigned int bitman_alloc(struct bitmap_manager *bm);
+void bitman_free(struct bitmap_manager *bm, unsigned int pos);

include/lib/bitmap.h

+/* Copyright (C) 2021 Rain */
+
+/* This file is part of Cunix. */
+
+/* 
+  Cunix is free software: you can redistribute it and/or modify 
+  it under the terms of the GNU General Public License as published by 
+  the Free Software Foundation, either version 3 of the License, or 
+  (at your option) and later version. 
+*/
+
+/*
+  Cunix is distributed in the hope that it will be useful, 
+  but WITHOUT ANY WARRANTY; without even the implied warranty of 
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 
+  GNU General Public License for more details. 
+*/
+
+/*
+  You should have received a copy of the GNU General Public License 
+   along with Cunix. If not, see <https://www.gnu.org/licenses/>.  
+*/
+
+
+
+
+extern char *bitmap_init(unsigned int size);
+extern void bitmap_set(unsigned char *bitmap, unsigned int pos, unsigned char value);
+extern char bitmap_read(unsigned char *bitmap, unsigned int pos);
+

kernel/hal/terminal.c → include/lib/rlib.h

@@ -24,3 +24,7 @@
 
 
 
+#include <lib/bitmap.h>
+#include <lib/bitman.h>
+
+

kernel/Makefile

 default:
 	make -C init/
 	make -C hal/
+	make -C lib/
 	make kernel.bin
 
-kernel.o: init/main.o hal/terminal.o
-	ld -b elf64-x86-64 -o kernel.o init/main.o hal/terminal.o -T kernel.lds
+kernel.o: init/main.o hal/vgatext/vgatext.o lib/bitmap.o lib/bitman.o init/print.o
+	ld -b elf64-x86-64 -o kernel.o init/main.o init/print.o hal/vgatext/vgatext.o lib/bitmap.o lib/bitman.o -T kernel.lds
 	
 kernel.bin: kernel.o
 	objcopy -I elf64-x86-64 -S -R ".eh_frame" -R ".comment" -O binary kernel.o kernel.bin
 
 
+clear:
+	make -C init/ clear
+	make -C hal/ clear
+	make -C lib/ clear
+	rm kernel.o kernel.bin
 

kernel/hal/Makefile

-C_FLAGS = -mcmodel=large -fno-builtin -m64 
-
-all: terminal.c
-
-%.o: %.c
-	gcc -c $*.c $(C_FLAGS)
+all: vgatext/vgatext.c 
+	make -C vgatext/
 
+clear:
+	make -C vgatext/ clear
 

kernel/hal/vgatext/Makefile

+C_FLAGS = -mcmodel=large -fno-builtin -m64 -I ../../../include
+
+
+all: vgatext.o
+
+
+%.o: %.c
+	gcc -c *$.c $(C_FLAGS)
+
+
+clear:
+	rm *.o
+

kernel/hal/vgatext/vgatext.c

+/* Copyright (C) 2021 Rain */
+
+/* This file is part of Cunix. */
+
+/* 
+  Cunix is free software: you can redistribute it and/or modify 
+  it under the terms of the GNU General Public License as published by 
+  the Free Software Foundation, either version 3 of the License, or 
+  (at your option) and later version. 
+*/
+
+/*
+  Cunix is distributed in the hope that it will be useful, 
+  but WITHOUT ANY WARRANTY; without even the implied warranty of 
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 
+  GNU General Public License for more details. 
+*/
+
+/*
+  You should have received a copy of the GNU General Public License 
+   along with Cunix. If not, see <https://www.gnu.org/licenses/>.  
+*/
+
+
+
+
+#include <kernel/init.h>
+#include <kernel/types.h>
+#include <kernel/errno.h>
+#include <kernel/module.h>
+
+#include <lib/rlib.h>
+#include <arch/io.h>
+
+#include <kernel/vgatext.h>
+
+
+
+
+__uint32_t next_fd = 1;
+
+struct inode_desc *vga_open(char *name, __uint32_t type, __uint32_t mode, errno_t *errno) {
+	*errno = -E_NOSUPP;
+}
+
+
+errno_t vga_creat(char *name, __uint32_t type, __uint32_t mode) {
+	return -E_NOSUPP;
+}
+
+
+errno_t vga_read(struct inode_desc *inode, char *buffer, __uint64_t l) {
+	return -E_HNOSUP;
+}
+
+
+void update_cursor(__uint32_t x, __uint32_t y) {
+	__uint16_t pos = y * TEXT_VGA_X + x;
+
+	outb(0x0f, 0x03d4);
+	outb((__uint8_t) (pos & 0xff), 0x03d5);
+	outb(0x0e, 0x03d4);
+	outb((__uint8_t) ((pos >> 8) & 0xff), 0x03d5);
+
+	return;
+}
+
+__uint16_t read_cursor(void) {
+	__uint16_t pos = 0;
+
+	outb(0x0f, 0x03d4);
+	pos |= inb(0x03d5);
+
+	outb(0x0e, 0x03d4);
+	pos |= ((__uint16_t) inb(0x03d5)) << 8;
+
+	return pos;
+}
+
+
+errno_t vga_fill(char *name, __uint32_t type, __uint32_t mode, struct vga_inode *inode) {
+	inode->inode.size = sizeof(struct vga_inode);
+	inode->inode.fd = next_fd;
+
+	inode->inode.off = 1 * TEXT_VGA_X + 0;
+
+	inode->fb = (__uint8_t *) 0xb8000;
+	inode->x = 0;
+
+	/* first line is in use */
+	inode->y = 1;
+
+	next_fd++;
+
+	update_cursor(0, 0);
+	
+	return 0;
+}
+
+
+errno_t vga_write(struct vga_inode *inode, char *buffer, __uint64_t l) {
+	/* for safety, we re-calc offset */
+	inode->inode.off = (inode->y * TEXT_VGA_X + inode->x) * 2;
+	
+	if (*buffer == '\n') {
+		/* we use LF to line feed, not CRLF in Windows */
+		inode->x = 0;
+		inode->y++;
+		update_cursor(inode->x, inode->y);
+
+		return 0;
+	}
+
+	if (*buffer == '\r') {
+		inode->x = 0;
+		update_cursor(inode->x, inode->y);
+	}
+
+
+	/* put it */
+
+	inode->fb[inode->inode.off] = *buffer;
+	/* color white */
+	inode->fb[inode->inode.off + 1] = 0x0f;
+
+	inode->inode.off += 2;
+
+	inode->x++;
+	if (inode->x == TEXT_VGA_X) {
+		inode->x = 0;
+		inode->y++;
+	}
+
+	update_cursor(inode->x, inode->y);
+
+	return 0;
+}
+
+
+errno_t vga_lseek(struct inode_desc *inode, __uint32_t off, __uint32_t seg) {
+	return -E_HNOSUP;
+}
+
+
+void vga_close(struct inode_desc *inode) {
+	/* disable cursor */
+	outb(0x3d4,  0x0a);
+	outb(0x3d5, 0x20);
+
+	return;
+}
+
+
+struct file_operations vga = INIT_MODULE(vga);
+

kernel/init/Makefile

-C_FLAGS = -mcmodel=large -fno-builtin -m64 
+C_FLAGS = -mcmodel=large -fno-builtin -m64 -I ../../include/
 
-all: main.o
+all: main.o print.o
 
 %.o: %.c
 	gcc -c $*.c $(C_FLAGS)
 
 
+clear:
+	rm *.o
+

kernel/init/main.c

@@ -24,12 +24,17 @@
 
 
 
-void init(void) {
-	unsigned long i;
+#include <kernel/init.h>
+#include <kernel/types.h>
+#include <kernel/errno.h>
+
+#include <kernel/vgatext.h>
+#include <kernel/print.h>
 
-	for (i = 0xa0000; i < 0xaffff; i++) {
-		*((char *) i) = 0x0f;
-	}
+void init(void) {
+	struct vga_inode vi;
+	vga.fill(NULL, 0, 0, &vi);
+	print(&vi, "kernel starting\n");
 
 	for (;;);
 }

kernel/init/print.c

+/* Copyright (C) 2021 Rain */
+
+/* This file is part of Cunix. */
+
+/* 
+  Cunix is free software: you can redistribute it and/or modify 
+  it under the terms of the GNU General Public License as published by 
+  the Free Software Foundation, either version 3 of the License, or 
+  (at your option) and later version. 
+*/
+
+/*
+  Cunix is distributed in the hope that it will be useful, 
+  but WITHOUT ANY WARRANTY; without even the implied warranty of 
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 
+  GNU General Public License for more details. 
+*/
+
+/*
+  You should have received a copy of the GNU General Public License 
+   along with Cunix. If not, see <https://www.gnu.org/licenses/>.  
+*/
+
+
+
+
+#include <kernel/init.h>
+#include <kernel/types.h>
+#include <kernel/errno.h>
+
+#include <kernel/vgatext.h>
+
+
+errno_t print(struct vga_inode *inode, char *s) {
+	for (; *s; s++) {
+		vga.write(inode, s, 1);
+	}
+
+	return 0;
+}

kernel/lib/Makefile

+C_FLAGS = -mcmodel=large -m64 -fno-builtin -nostdlib -I ../../include/
+
+all: bitmap.c bitman.c bitmap.o bitman.o 
+
+%.o: %.c
+	gcc -c $*.c $(C_FLAGS)
+
+
+clear:
+	rm *.o
+

kernel/lib/bitman.c

+/* Copyright (C) 2021 Rain */
+
+/* This file is part of Cunix. */
+
+/* 
+  Cunix is free software: you can redistribute it and/or modify 
+  it under the terms of the GNU General Public License as published by 
+  the Free Software Foundation, either version 3 of the License, or 
+  (at your option) and later version. 
+*/
+
+/*
+  Cunix is distributed in the hope that it will be useful, 
+  but WITHOUT ANY WARRANTY; without even the implied warranty of 
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 
+  GNU General Public License for more details. 
+*/
+
+/*
+  You should have received a copy of the GNU General Public License 
+   along with Cunix. If not, see <https://www.gnu.org/licenses/>.  
+*/
+
+
+
+
+#include <lib/rlib.h>
+
+
+/*
+	find a new bit in bm->bitmap. 
+
+	STEPS: 
+		1. save free position. 
+		2. find a new free position. 
+		3. save new free position. 
+*/
+unsigned int bitman_alloc(struct bitmap_manager *bm) {
+	unsigned int p = bm->next_free;
+	bitmap_set(bm->bitmap, bm->next_free, 1);
+
+	for (; bitmap_read(bm->bitmap, bm->next_free) == 1; bm->next_free++);
+
+	return p;
+}
+
+
+/*
+	free a bit. 
+
+	STEPS: 
+		1. free bit pos. 
+		2. if pos is lowwer than bm->next_free
+			2a. set bm->next_free = pos. 
+*/
+void bitman_free(struct bitmap_manager *bm, unsigned int pos) {
+	bitmap_set(bm->bitmap, pos, 0);
+
+	if (pos < bm->next_free) {
+		bm->next_free = pos;
+	}
+	return;
+}

kernel/lib/bitmap.c

+/* Copyright (C) 2021 Rain */
+
+/* This file is part of Cunix. */
+
+/* 
+  Cunix is free software: you can redistribute it and/or modify 
+  it under the terms of the GNU General Public License as published by 
+  the Free Software Foundation, either version 3 of the License, or 
+  (at your option) and later version. 
+*/
+
+/*
+  Cunix is distributed in the hope that it will be useful, 
+  but WITHOUT ANY WARRANTY; without even the implied warranty of 
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 
+  GNU General Public License for more details. 
+*/
+
+/*
+  You should have received a copy of the GNU General Public License 
+   along with Cunix. If not, see <https://www.gnu.org/licenses/>.  
+*/
+
+
+
+
+#include <kernel/types.h>
+
+void bitmap_set(unsigned char *bitmap, unsigned int pos, unsigned char value) {
+	unsigned char mask = 0x80 >> (pos & 0x7);
+	if (value) {
+		bitmap[pos >> 3] |= mask;
+	}
+	else {
+		bitmap[pos >> 3] &= ~mask;
+	}
+}
+
+char bitmap_read(unsigned char *bitmap, unsigned int pos) {
+	unsigned char mask = 0x80 >> (pos & 0x7);
+
+	return (mask & bitmap[pos >> 3]) == mask ? 1 : 0;
+}
+