From b631f251defe2b2f7075e743f7f328cbfed5766b Mon Sep 17 00:00:00 2001
From: Baptiste Wicht <baptiste.wicht@gmail.com>
Date: Wed, 10 Aug 2016 22:17:02 +0200
Subject: [PATCH] Complete ramdisk implementation

---
 kernel/include/ramdisk.hpp |  6 +++--
 kernel/src/disks.cpp       |  2 +-
 kernel/src/ramdisk.cpp     | 53 +++++++++++++++++++++++++++++++++++---
 3 files changed, 54 insertions(+), 7 deletions(-)

diff --git a/kernel/include/ramdisk.hpp b/kernel/include/ramdisk.hpp
index 114c6335..1cdc38ab 100644
--- a/kernel/include/ramdisk.hpp
+++ b/kernel/include/ramdisk.hpp
@@ -16,10 +16,12 @@ namespace ramdisk {
 
 struct disk_descriptor {
     uint64_t id;
-    //TODO
+    uint64_t max_size;
+    uint64_t pages;
+    char** allocated;
 };
 
-disk_descriptor* make_disk();
+disk_descriptor* make_disk(uint64_t max_size);
 
 struct ramdisk_driver : devfs::dev_driver {
     size_t read(void* data, char* buffer, size_t count, size_t offset, size_t& read);
diff --git a/kernel/src/disks.cpp b/kernel/src/disks.cpp
index 71cca193..78c224cc 100644
--- a/kernel/src/disks.cpp
+++ b/kernel/src/disks.cpp
@@ -57,7 +57,7 @@ devfs::dev_driver* ramdisk_driver = &ramdisk_driver_impl;
 devfs::dev_driver* atapi_driver = nullptr;
 
 void make_ram_disk(){
-    auto* descriptor = ramdisk::make_disk();
+    auto* descriptor = ramdisk::make_disk(1024 * 1024); //1MiB
 
     if(!descriptor){
         logging::logf(logging::log_level::ERROR, "disks: failed to created /dev/ram0");
diff --git a/kernel/src/ramdisk.cpp b/kernel/src/ramdisk.cpp
index 024cba03..875af878 100644
--- a/kernel/src/ramdisk.cpp
+++ b/kernel/src/ramdisk.cpp
@@ -8,6 +8,8 @@
 #include "ramdisk.hpp"
 #include "errors.hpp"
 #include "disks.hpp"
+#include "paging.hpp"
+#include "logging.hpp"
 
 namespace {
 
@@ -18,14 +20,17 @@ ramdisk::disk_descriptor ramdisks[MAX_RAMDISK];
 
 } //end of anonymous namespace
 
-ramdisk::disk_descriptor* ramdisk::make_disk(){
+ramdisk::disk_descriptor* ramdisk::make_disk(uint64_t max_size){
     if(current == MAX_RAMDISK){
         return nullptr;
     }
 
-    ramdisks[current].id = current;
+    auto pages = paging::pages(max_size);
 
-    //TODO
+    ramdisks[current].id = current;
+    ramdisks[current].max_size = max_size;
+    ramdisks[current].pages = pages;
+    ramdisks[current].allocated = new char*[pages];
 
     ++current;
     return &ramdisks[current - 1];
@@ -37,7 +42,27 @@ size_t ramdisk::ramdisk_driver::read(void* data, char* destination, size_t count
     auto descriptor = reinterpret_cast<disks::disk_descriptor*>(data);
     auto disk = reinterpret_cast<ramdisk::disk_descriptor*>(descriptor->descriptor);
 
-    return std::ERROR_INVALID_COUNT;
+    if(offset + count >= disk->max_size){
+        logging::logf(logging::log_level::ERROR, "ramdisk: Tried to read too far\n");
+        return std::ERROR_INVALID_OFFSET;
+    }
+
+    while(read != count){
+        auto page = offset / paging::PAGE_SIZE;
+
+        if(!disk->allocated[page]){
+            disk->allocated[page] = new char[paging::PAGE_SIZE];
+            std::fill_n(disk->allocated[page], paging::PAGE_SIZE, 0);
+        }
+
+        auto to_read = std::min(paging::PAGE_SIZE, count - read);
+        std::copy_n(destination, disk->allocated[page], to_read);
+        read += to_read;
+
+        offset += paging::PAGE_SIZE;
+    }
+
+    return 0;
 }
 
 size_t ramdisk::ramdisk_driver::write(void* data, const char* source, size_t count, size_t offset, size_t& written){
@@ -46,5 +71,25 @@ size_t ramdisk::ramdisk_driver::write(void* data, const char* source, size_t cou
     auto descriptor = reinterpret_cast<disks::disk_descriptor*>(data);
     auto disk = reinterpret_cast<ramdisk::disk_descriptor*>(descriptor->descriptor);
 
+    if(offset + count >= disk->max_size){
+        logging::logf(logging::log_level::ERROR, "ramdisk: Tried to write too far\n");
+        return std::ERROR_INVALID_OFFSET;
+    }
+
+    while(written != count){
+        auto page = offset / paging::PAGE_SIZE;
+
+        if(!disk->allocated[page]){
+            disk->allocated[page] = new char[paging::PAGE_SIZE];
+            std::fill_n(disk->allocated[page], paging::PAGE_SIZE, 0);
+        }
+
+        auto to_write = std::min(paging::PAGE_SIZE, count - written);
+        std::copy_n(disk->allocated[page], source, to_write);
+        written += to_write;
+
+        offset += paging::PAGE_SIZE;
+    }
+
     return std::ERROR_INVALID_COUNT;
 }