3 files changed, 111 insertions, 1 deletions
diff --git a/kernel/Makefile b/kernel/Makefile
index ca19d29..ffa835a 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -1,6 +1,6 @@
 CC="i686-sb-gcc"
 AS="i686-sb-as"
-OBJ = arch/i386/boot.o init/kernel.o cpu/gdt.o cpu/reload_gdt.o cpu/idt.o cpu/io.o libc/stdio/print.o drivers/keyboard.o log.o drivers/pit.o libc/string/memcpy.o libc/string/strlen.o libc/string/memcmp.o drivers/ata.o libc/string/memset.o cpu/syscall.o  read_eip.o libc/exit/assert.o process.o libc/string/strcpy.o arch/i386/mmu.o kmalloc.o fs/ext2.o fs/vfs.o fs/devfs.o cpu/spinlock.o random.o libc/string/strcmp.o crypto/ChaCha20/chacha20.o crypto/SHA1/sha1.o fs/tmpfs.o libc/string/isequal.o drivers/pst.o syscalls/ppoll.o syscalls/ftruncate.o kubsan.o syscalls/mmap.o drivers/serial.o syscalls/accept.o syscalls/bind.o syscalls/socket.o socket.o poll.o fs/fifo.o hashmap/hashmap.o fs/shm.o syscalls/shm.o elf.o ksbrk.o sched/scheduler.o syscalls/fstat.o libc/string/copy.o drivers/mouse.o libc/string/strlcpy.o libc/string/strcat.o drivers/vbe.o syscalls/msleep.o syscalls/uptime.o syscalls/mkdir.o drivers/pci.o drivers/rtl8139.o network/ethernet.o network/arp.o network/bytes.o network/ipv4.o network/udp.o syscalls/recvfrom.o math.o syscalls/sendto.o signal.o syscalls/kill.o syscalls/sigaction.o network/tcp.o drivers/ahci.o crypto/xoshiro256plusplus/xoshiro256plusplus.o syscalls/chdir.o syscalls/getcwd.o syscalls/isatty.o syscalls/randomfill.o syscalls/open.o syscalls/write.o syscalls/pwrite.o syscalls/port.o syscalls/map_frames.o syscalls/virtual_to_physical.o syscalls/install_irq.o arch/i386/interrupts.o cpu/isr.o lib/stack.o lib/buffered_write.o lib/list.o cpu/arch_inst.o cpu/int_syscall.o queue.o syscalls/queue.o syscalls/munmap.o syscalls/open_process.o syscalls/lseek.o
+OBJ = arch/i386/boot.o init/kernel.o cpu/gdt.o cpu/reload_gdt.o cpu/idt.o cpu/io.o libc/stdio/print.o drivers/keyboard.o log.o drivers/pit.o libc/string/memcpy.o libc/string/strlen.o libc/string/memcmp.o drivers/ata.o libc/string/memset.o cpu/syscall.o  read_eip.o libc/exit/assert.o process.o libc/string/strcpy.o arch/i386/mmu.o kmalloc.o fs/ext2.o fs/vfs.o fs/devfs.o cpu/spinlock.o random.o libc/string/strcmp.o crypto/ChaCha20/chacha20.o crypto/SHA1/sha1.o fs/tmpfs.o libc/string/isequal.o drivers/pst.o syscalls/ppoll.o syscalls/ftruncate.o kubsan.o syscalls/mmap.o drivers/serial.o syscalls/accept.o syscalls/bind.o syscalls/socket.o socket.o poll.o fs/fifo.o hashmap/hashmap.o fs/shm.o syscalls/shm.o elf.o ksbrk.o sched/scheduler.o syscalls/fstat.o libc/string/copy.o drivers/mouse.o libc/string/strlcpy.o libc/string/strcat.o drivers/vbe.o syscalls/msleep.o syscalls/uptime.o syscalls/mkdir.o drivers/pci.o drivers/rtl8139.o network/ethernet.o network/arp.o network/bytes.o network/ipv4.o network/udp.o syscalls/recvfrom.o math.o syscalls/sendto.o signal.o syscalls/kill.o syscalls/sigaction.o network/tcp.o drivers/ahci.o crypto/xoshiro256plusplus/xoshiro256plusplus.o syscalls/chdir.o syscalls/getcwd.o syscalls/isatty.o syscalls/randomfill.o syscalls/open.o syscalls/write.o syscalls/pwrite.o syscalls/port.o syscalls/map_frames.o syscalls/virtual_to_physical.o syscalls/install_irq.o arch/i386/interrupts.o cpu/isr.o lib/stack.o lib/buffered_write.o lib/list.o cpu/arch_inst.o cpu/int_syscall.o queue.o syscalls/queue.o syscalls/munmap.o syscalls/open_process.o syscalls/lseek.o lib/ringbuffer.o
 CFLAGS = -std=c99 -O0 -fsanitize=vla-bound,shift-exponent,pointer-overflow,shift,signed-integer-overflow,bounds -ggdb -ffreestanding -Wall -Wextra -Wno-int-conversion -Wno-unused-parameter -Werror -mgeneral-regs-only -Wimplicit-fallthrough -I./libc/include/ -I. -Wno-pointer-sign -DKERNEL
 LDFLAGS=
 INCLUDE=-I./includes/ -I../include/ -I./libc/include/
diff --git a/kernel/lib/ringbuffer.c b/kernel/lib/ringbuffer.c
new file mode 100644
index 0000000..425971d
--- /dev/null
+++ b/kernel/lib/ringbuffer.c
@@ -0,0 +1,94 @@
+#include <assert.h>
+#include <kmalloc.h>
+#include <lib/ringbuffer.h>
+#include <math.h>
+#include <string.h>
+
+int ringbuffer_init(struct ringbuffer *rb, u32 buffer_size) {
+  rb->buffer_size = 0;
+  rb->read_ptr = 0;
+  rb->write_ptr = 0;
+  rb->buffer = kmalloc(buffer_size);
+  if (!rb->buffer) {
+    return 0;
+  }
+  rb->buffer_size = buffer_size;
+  return 1;
+}
+
+u32 ringbuffer_write(struct ringbuffer *rb, const u8 *buffer, u32 len) {
+  const u32 orig_len = len;
+  for (; len > 0;) {
+    u32 buffer_left;
+    if (rb->write_ptr >= rb->read_ptr) {
+      buffer_left = rb->buffer_size - rb->write_ptr;
+      if (0 == rb->read_ptr && buffer_left > 0) {
+        buffer_left--;
+      }
+    } else {
+      buffer_left = (rb->read_ptr - rb->write_ptr - 1);
+    }
+
+    if (0 == buffer_left) {
+      break;
+    }
+
+    u32 write_len = min(len, buffer_left);
+    write_len = min(write_len, rb->buffer_size - rb->write_ptr);
+    memcpy(rb->buffer + rb->write_ptr, buffer, write_len);
+    buffer += write_len;
+    len -= write_len;
+    rb->write_ptr = (rb->write_ptr + write_len) % rb->buffer_size;
+  }
+  return orig_len - len;
+}
+
+u32 ringbuffer_read(struct ringbuffer *rb, u8 *buffer, u32 len) {
+  const u32 orig_len = len;
+  for (; len > 0;) {
+    if (rb->read_ptr == rb->write_ptr) {
+      break;
+    }
+    u32 read_len;
+    if (rb->read_ptr >= rb->write_ptr) {
+      read_len = rb->buffer_size - rb->read_ptr;
+    } else if (rb->read_ptr < rb->write_ptr) {
+      read_len = rb->write_ptr - rb->read_ptr;
+    }
+    read_len = min(len, read_len);
+
+    memcpy(buffer, rb->buffer + rb->read_ptr, read_len);
+    len -= read_len;
+    buffer += read_len;
+    rb->read_ptr = (rb->read_ptr + read_len) % rb->buffer_size;
+  }
+  return orig_len - len;
+}
+
+void ringbuffer_free(struct ringbuffer *rb) {
+  kfree(rb->buffer);
+  rb->buffer = NULL;
+  rb->buffer_size = 0;
+  rb->write_ptr = 0;
+  rb->read_ptr = 0;
+}
+
+#ifdef KERNEL_TEST
+void ringbuffer_test(void) {
+  char buffer[4096];
+  struct ringbuffer rb;
+  assert(ringbuffer_init(&rb, 6));
+  assert(2 == ringbuffer_write(&rb, "ab", 2));
+  assert(2 == ringbuffer_write(&rb, "cd", 2));
+  assert(1 == ringbuffer_write(&rb, "ef", 2));
+  assert(0 == ringbuffer_write(&rb, "gh", 2));
+  assert(2 == ringbuffer_read(&rb, buffer, 2));
+  assert(0 == memcmp(buffer, "ab", 2));
+  assert(2 == ringbuffer_read(&rb, buffer, 2));
+  assert(0 == memcmp(buffer, "cd", 2));
+  assert(1 == ringbuffer_read(&rb, buffer, 2));
+  assert(0 == memcmp(buffer, "e", 1));
+  assert(0 == ringbuffer_read(&rb, buffer, 2));
+  ringbuffer_free(&rb);
+}
+#endif // KERNEL_TEST
diff --git a/kernel/lib/ringbuffer.h b/kernel/lib/ringbuffer.h
new file mode 100644
index 0000000..c329af3
--- /dev/null
+++ b/kernel/lib/ringbuffer.h
@@ -0,0 +1,16 @@
+#include <typedefs.h>
+
+struct ringbuffer {
+  u8 *buffer;
+  u32 buffer_size;
+  u32 read_ptr;
+  u32 write_ptr;
+};
+
+int ringbuffer_init(struct ringbuffer *rb, u32 buffer_size);
+u32 ringbuffer_write(struct ringbuffer *rb, const u8 *buffer, u32 len);
+u32 ringbuffer_read(struct ringbuffer *rb, u8 *buffer, u32 len);
+void ringbuffer_free(struct ringbuffer *rb);
+#ifdef KERNEL_TEST
+void ringbuffer_test(void);
+#endif // KERNEL_TEST