From 018c83575fa32c71e62adb4e0e969d60efafe7cb Mon Sep 17 00:00:00 2001
From: Recolic Keghart <root@recolic.net>
Date: Sun, 2 May 2021 22:24:53 +0800
Subject: [PATCH] allocator
---
kernel/Makefile | 2 +-
kernel/include/kutils.hpp | 94 +++++++++++++++++++++++++--------------
kernel/include/stdint.hpp | 4 ++
kernel/include/stdlib.hpp | 9 +++-
kernel/include/vga.hpp | 4 +-
kernel/kernel.cc | 14 ++++++
6 files changed, 89 insertions(+), 38 deletions(-)
diff --git a/kernel/Makefile b/kernel/Makefile
index ade032a..6796ba7 100644
--- a/kernel/Makefile
+++ b/kernel/Makefile
@@ -15,7 +15,7 @@ head:
nasm -f elf$(BITS) -DTARGET_BITS=$(BITS) image_head.asm -o image_head.o
kernel:
- g++ -ffreestanding -fpie -c kernel.cc -o kernel.o -m$(BITS) -std=c++17
+ g++ -ffreestanding -fpie -fno-exceptions -c kernel.cc -o kernel.o -m$(BITS) -std=c++17
clean:
rm -f *.o *.img
diff --git a/kernel/include/kutils.hpp b/kernel/include/kutils.hpp
index 9a8932e..7d1c983 100644
--- a/kernel/include/kutils.hpp
+++ b/kernel/include/kutils.hpp
@@ -9,18 +9,19 @@ namespace impl {
constexpr uint64_t kalloc_end_addr = 0x200000;
// Currently 1MB, must be paged.
- struct __attribute__((packed)) free_slot_head_t {
+ struct __attribute__((packed)) free_slot_header_t {
uint32_t size;
uint64_t next; // 0x0 means tail.
};
- static_assert(sizeof(free_slot_head_t) == sizeof(uint32_t) + sizeof(uint64_t));
+ static_assert(sizeof(free_slot_header_t) == sizeof(uint32_t) + sizeof(uint64_t));
- using allocated_slot_head_t = uint32_t; // contains size EXCEPT the head!
+ using allocated_slot_header_t = uint32_t; // contains size EXCEPT the head!
inline void kalloc_init_pool() {
+ // Just create a single huge slot, which contains the whole pool.
struct __attribute__((packed)) _kalloc_head {
uint32_t magic = 0x12230823;
- free_slot_head_t free_slot_head {kalloc_end_addr - kalloc_begin_addr - sizeof(_kalloc_head), 0x0};
+ free_slot_header_t free_slot_head {kalloc_end_addr - kalloc_begin_addr - sizeof(_kalloc_head), 0x0};
} kalloc_head;
static_assert(sizeof(kalloc_head) == sizeof(uint32_t)*2 + sizeof(uint64_t));
@@ -28,57 +29,84 @@ namespace impl {
}
}
-// naive kalloc
+// naive kalloc. We keep a list of free slot.
+// The return value is NULL on failure, and is a valid pointer `p` on success.
+// ((allocated_slot_header_t *)p)[-1] contains the header, which records the allocated size.
+// and ((char *)p)[0:requested_size] is available for use.
inline void *kalloc_impl(const uint32_t requested_size) {
- const auto req_size_with_head = requested_size + sizeof(impl::allocated_slot_head_t);
+ const auto req_size_with_head = requested_size + sizeof(impl::allocated_slot_header_t);
uint64_t prev_slot_addr = 0x0;
- auto curr_slot_addr = impl::kalloc_begin_addr + sizeof(impl::free_slot_head_t::size);
+ // Locate first free slot.
+ auto curr_slot_addr = impl::kalloc_begin_addr + sizeof(impl::free_slot_header_t::size);
while(true) {
- auto curr_slot = (impl::free_slot_head_t *)curr_slot_addr;
- if(curr_slot->size >= req_size_with_head) {
- if(curr_slot->size < 32 + req_size_with_head) {
- // Give the whole slot
+ // Iterate all free slots. It's slow, but good enough for a toy.
+ auto curr_freeslot_header_ptr = (impl::free_slot_header_t *)curr_slot_addr;
+ if(curr_freeslot_header_ptr->size >= req_size_with_head) {
+ // Good. We can do the allocate now!
+ decltype(impl::free_slot_header_t::size) actually_assigned_size;
+ decltype(curr_slot_addr) allocated_slot_addr;
+ if(curr_freeslot_header_ptr->size < 32 + req_size_with_head) {
+ // Give the current slot.
if(prev_slot_addr == 0x0) {
- // No previous slot. I am the first one.
- // Never give the WHOLE first slot. Try again.
- goto _kalloc_failed_try_again;
+ // The first slot must be a valid free_slot_head. It's required
+ // to locate the next free_slot.
+ curr_freeslot_header_ptr->size = 0;
+ // Is this case, the space of free_slot_head is not available.
+ actually_assigned_size = curr_freeslot_header_ptr->size;
+ allocated_slot_addr = curr_slot_addr + sizeof(impl::free_slot_header_t);
}
- // Do the alloc
else {
- curr_slot->size -= req_size_with_head;
- auto prev_slot = (impl::free_slot_head_t *)prev_slot_addr;
- prev_slot->next = curr_slot->next;
+ // Eliminate the current free_slot_head.
+ curr_freeslot_header_ptr->size -= req_size_with_head;
+ auto prev_slot = (impl::free_slot_header_t *)prev_slot_addr;
+ prev_slot->next = curr_freeslot_header_ptr->next;
+ // Is this case, the space of free_slot_head is available.
+ actually_assigned_size = curr_freeslot_header_ptr->size + sizeof(impl::free_slot_header_t);
+ allocated_slot_addr = curr_slot_addr;
}
- const auto actually_assigned_size = sizeof(impl::free_slot_head_t) + curr_slot->size;
- *(impl::allocated_slot_head_t *)curr_slot_addr = actually_assigned_size;
- return (char *)curr_slot_addr + sizeof(impl::allocated_slot_head_t);
}
else {
- // Shrink the slot.
- // Do the alloc
- // TODO
- curr_slot->size -= req_size_with_head;
- return (char *)curr_slot_addr + curr_slot->size;
+ // The slot is too large. Shrink the free_slot, and give the tail space as result.
+ curr_freeslot_header_ptr->size -= req_size_with_head;
+ actually_assigned_size = req_size_with_head;
+ allocated_slot_addr = curr_slot_addr + sizeof(impl::free_slot_header_t) + curr_freeslot_header_ptr->size;
}
+ // Create the allocated_slot_head structure.
+ *(impl::allocated_slot_header_t *)allocated_slot_addr = actually_assigned_size - sizeof(impl::allocated_slot_header_t);
+ return (char *)allocated_slot_addr + sizeof(impl::allocated_slot_header_t);
}
- else if (curr_slot->next != 0x0){
- // Failed. Next.
-_kalloc_failed_try_again:
+ else if (curr_freeslot_header_ptr->next != 0x0){
+ // Failed. Try next slot.
prev_slot_addr = curr_slot_addr;
- curr_slot_addr = curr_slot->next;
+ curr_slot_addr = curr_freeslot_header_ptr->next;
continue;
}
else {
- // No memory
- return 0x0;
+ // We're already at the end. Return NO_MEMORY.
+ return NULL;
}
}
}
-
inline void kfree(void *memory) {
}
+template <typename T>
+struct kallocator {
+ using value_type = T;
+ kallocator() noexcept {}
+ template <typename AnyType> kallocator (const kallocator &) noexcept {}
+ template <typename AnyType> kallocator (kallocator &&) noexcept {}
+
+ T *allocate(uint32_t count) {
+ return (T*)kalloc_impl(sizeof(T) * count);
+ }
+
+ void deallocate (T* p, uint32_t) {
+ kfree(p);
+ }
+};
+
#endif
diff --git a/kernel/include/stdint.hpp b/kernel/include/stdint.hpp
index a3e534d..aaf4c5f 100644
--- a/kernel/include/stdint.hpp
+++ b/kernel/include/stdint.hpp
@@ -1,3 +1,7 @@
+
+#include <stdint.h>
+#define ROS_KERN_STDINT_HPP
+
#ifndef ROS_KERN_STDINT_HPP
#define ROS_KERN_STDINT_HPP
diff --git a/kernel/include/stdlib.hpp b/kernel/include/stdlib.hpp
index dfeffc2..d08db89 100644
--- a/kernel/include/stdlib.hpp
+++ b/kernel/include/stdlib.hpp
@@ -3,14 +3,18 @@
#include "stdint.hpp"
+#ifndef NULL
+#define NULL 0
+#endif
+
template <typename T>
-inline void memcpy(T *dst, const T *src, size_t count) {
+inline void memcpy(T *dst, const T *src, uint32_t count) {
for(auto i = 0; i < count; ++i) {
dst[i] = src[i];
}
}
template <typename T>
-inline void memset(T *dst, const T &data_to_set, size_t count) {
+inline void memset(T *dst, const T &data_to_set, uint32_t count) {
char *cdst = reinterpret_cast<char *>(dst);
for(auto i = 0; i < count; ++i) {
@@ -19,4 +23,5 @@ inline void memset(T *dst, const T &data_to_set, size_t count) {
}
+
#endif
diff --git a/kernel/include/vga.hpp b/kernel/include/vga.hpp
index ffb9f25..a985ba1 100644
--- a/kernel/include/vga.hpp
+++ b/kernel/include/vga.hpp
@@ -24,7 +24,7 @@ inline void set_char(uint16_t x, uint16_t y, char c, char color) {
VGA_BEGIN_ADDR[y*VGA_WIDTH + x] = VGA_MAKE_CHAR(c, color);
}
-inline void put_char(char c, uint8_t color) {
+inline void print_char(char c, uint8_t color = default_color) {
static uint16_t pos = 0;
if(pos >= VGA_WIDTH * VGA_HEIGHT)
trigger_scroll(&pos);
@@ -43,7 +43,7 @@ inline void put_char(char c, uint8_t color) {
inline void print(const char *cstr, uint8_t color = default_color) {
while(*cstr != '\0') {
- put_char(*(cstr++), color);
+ print_char(*(cstr++), color);
}
}
diff --git a/kernel/kernel.cc b/kernel/kernel.cc
index 3fe8438..47fdb41 100644
--- a/kernel/kernel.cc
+++ b/kernel/kernel.cc
@@ -4,6 +4,8 @@
#include "include/bus_io.hpp"
#include "include/kutils.hpp"
+#include <string>
+
void test_dummy_function() {
auto tmp = read_byte_from_bus(0x3f2);
tmp |= 0x08;
@@ -15,11 +17,23 @@ void kernel_init() {
}
void main() {
+ kernel_init();
+
clear_screen();
print("Hello world!\n");
print("Hello world!\n", 0xb1);
print("Hello world!\n", 0xae);
print("Hello world!\n", 0x5c);
print("Hello world! This is recolic's test message, \n");
+
+ // std::array<uint32_t, 32> test_buf;
+ // uint32_t * test_buf = (uint32_t *)kalloc_impl(sizeof(uint32_t) * 32);
+ // for(auto i = 0; i < 32; ++i) {
+ // test_buf[i] = i == 0 ? 1 : test_buf[i-1]*2+1;
+ // print_char('0' + test_buf[i], default_color);
+ // }
+ // std::string s = "cxxhello world";
+ std::basic_string<char, std::char_traits<char>, kallocator<char>> s = "cxx hello world";
+ print(s.c_str());
}
--
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