1 files changed, 184 insertions, 19 deletions

diff --git a/src/kernel/task.c b/src/kernel/task.c
index 942d1c4..ab08e6b 100644
--- a/src/kernel/task.c
+++ b/src/kernel/task.c
@@ -1,6 +1,8 @@
+#include "paging.h"
 #include "panic.h"
+#include "pmap.h"
 #include "task.h"
-#include "paging.h"
+#include "util.h"
 #include "log.h"
 
 struct tss {
@@ -42,7 +44,7 @@ struct tss {
 
 #define MAX_TASKS 64
 
-static struct task_state tasks[MAX_TASKS];
+struct task_state tasks[MAX_TASKS];
 struct task_state *active_task;
 
 void init_tasks() {
@@ -68,31 +70,68 @@ uint32_t new_task(struct task_state state) {
   for (uint8_t n = 0; n < MAX_TASKS; ++n)
     if (!tasks[n].page_directory) {
       tasks[n] = state;
+      tasks[n].waiting = false;
+      for (uint8_t i = 0; i < MAX_WAITS; ++i)
+        tasks[n].waits[i].mode = NONE;
       return n + 1;
     }
   PANIC("Maximum number of tasks reached.");
 }
 
+static void tmp_halt() {
+//logf(LOG_INFO, "scheduler halting");
+  TSS->esp0 = 0x0003c000;
+  asm("sti\n"
+      "hlt\n"
+      "cli");
+  TSS->esp0 = 0x00040000;
+//logf(LOG_INFO, "scheduler resumed");
+}
+
 void advance_active_task() {
-  do
+//logf(LOG_INFO, "entered scheduler from \"%s\"", active_task->name);
+  struct task_state *old_task = active_task;
+  while (1) {
     if (++active_task == tasks + MAX_TASKS)
       active_task = tasks;
-  while (!active_task->page_directory || active_task->wait_mode);
+    if (active_task->page_directory && !active_task->waiting) {
+    //logf(LOG_INFO, "exiting scheduler to \"%s\"", active_task->name);
+      return;
+    }
+    if (active_task == old_task)
+      tmp_halt();
+  }
 }
 
 void make_sure_tasks() {
   for (uint8_t n = 0; n < MAX_TASKS; ++n)
     if (tasks[n].page_directory)
-      while (1) {
-        for (uint8_t n = 0; n < MAX_TASKS; ++n)
-          if (tasks[n].page_directory && !tasks[n].wait_mode)
-            return;
-        asm ("hlt");
-      }
-  set_log_mode(LOG_SYSTEM);
-  logsz("No tasks, halting.");
+      return;
+  logf(LOG_INFO, "No tasks, halting.");
   while (1)
-    asm ("hlt");
+    asm("hlt");
+}
+
+//IPC stuff isn't fully implemented, or tested in this version.
+//i'm planning to finish and make use of it in the next version,
+//making the terminal its own application instead of a library.
+
+#define MAX_IPC_PIPES 1024
+#define IPC_BUFFER_PAGES 1
+
+struct ipc_pipe {
+  void *buffer;
+  void *buffer_next_send;
+  const void *buffer_next_read;
+
+  uint32_t sender_handle;
+  uint32_t reader_handle;
+  bool delete_when_empty;
+} ipc_pipes[MAX_IPC_PIPES];
+
+void delete_pipe(struct ipc_pipe *pipe) {
+  free_pages(pipe->buffer, IPC_BUFFER_PAGES);
+  pipe->buffer = 0;
 }
 
 void delete_task(struct task_state *state) {
@@ -101,10 +140,136 @@ void delete_task(struct task_state *state) {
   switch_to_task_cr3();
   state->page_directory = 0;
 
-  uint32_t handle = state - tasks + 1;
-  for (uint8_t n = 0; n < MAX_TASKS; ++n)
-    if (tasks[n].page_directory &&
-       (tasks[n].wait_mode == PROCESS_END) &&
-       (tasks[n].wait_arg == handle))
-      tasks[n].wait_mode = NONE;
+  unwait_any((struct wait){.mode = PROCESS_END, .task = state});
+  unwait_any((struct wait){.mode = IPC_RECEIVE, .task = state});
+  unwait_any((struct wait){.mode = IPC_SEND,    .task = state});
+
+  const uint32_t handle = active_task - tasks + 1;
+  for (struct ipc_pipe *pipe = ipc_pipes; pipe < ipc_pipes + MAX_IPC_PIPES; ++pipe)
+    if (pipe->buffer) {
+      if (pipe->reader_handle == handle)
+        delete_pipe(pipe);
+      else if (pipe->sender_handle == handle) {
+        if (pipe->buffer_next_read == pipe->buffer_next_send)
+          delete_pipe(pipe);
+        else
+          pipe->delete_when_empty = true;
+      }
+    }
+}
+
+uint32_t find_unread_ipc() {
+  const uint32_t r_handle = active_task - tasks + 1;
+  for (struct ipc_pipe *pipe = ipc_pipes; pipe < ipc_pipes + MAX_IPC_PIPES; ++pipe)
+    if (pipe->buffer && (pipe->reader_handle == r_handle) &&
+        (pipe->buffer_next_read != pipe->buffer_next_send))
+      return pipe->sender_handle;
+  return 0;
+}
+
+struct ipc_pipe *get_existing_pipe(uint32_t sender_handle, uint32_t reader_handle) {
+  for (struct ipc_pipe *i = ipc_pipes; i < ipc_pipes + MAX_IPC_PIPES; ++i)
+    if (i->buffer && (i->sender_handle == sender_handle) &&
+                     (i->reader_handle == reader_handle))
+      return i;
+  return 0;
+}
+
+uint32_t ipc_send(uint32_t reader_handle, uint32_t count, const void *buffer) {
+  if (!reader_handle || !tasks[reader_handle - 1].page_directory)
+    return -1;
+
+  const uint32_t our_handle = active_task - tasks + 1;
+  struct ipc_pipe *pipe = get_existing_pipe(our_handle, reader_handle);
+  if (!pipe) {
+    for (struct ipc_pipe *i = ipc_pipes; i < ipc_pipes + MAX_IPC_PIPES; ++i)
+      if (!i->buffer) {
+        i->buffer = allocate_kernel_pages(IPC_BUFFER_PAGES);
+        i->buffer_next_read = i->buffer;
+        i->buffer_next_send = i->buffer;
+        i->reader_handle = reader_handle;
+        i->sender_handle = our_handle;
+        i->delete_when_empty = false;
+        pipe = i;
+        break;
+      }
+    if (!pipe)
+      PANIC("out of ipc pipes");
+  }
+
+  unwait(tasks + reader_handle - 1, (struct wait){.mode = IPC_RECEIVE, .task = active_task});
+  unwait(tasks + reader_handle - 1, (struct wait){.mode = IPC_RECEIVE_ANY});
+
+  uint32_t send_left = pipe->buffer_next_read - pipe->buffer_next_send - 1;
+  if (send_left < 0)
+    send_left += 4096 * IPC_BUFFER_PAGES;
+  if (count > send_left)
+    count = send_left;
+
+  if (pipe->buffer_next_send + count < pipe->buffer + 4096 * IPC_BUFFER_PAGES) {
+    memcpy(pipe->buffer_next_send, buffer, count);
+    pipe->buffer_next_send += count;
+    return count;
+  }
+
+  const uint32_t first_batch = pipe->buffer + 4096 * IPC_BUFFER_PAGES - pipe->buffer_next_send;
+  memcpy(pipe->buffer_next_send, buffer, first_batch);
+  memcpy(pipe->buffer, buffer + first_batch, count - first_batch);
+  pipe->buffer_next_send += count - 4096;
+  return count;
+}
+
+uint32_t ipc_read(uint32_t sender_handle, uint32_t count, void *buffer) {
+  if (!sender_handle || !tasks[sender_handle - 1].page_directory)
+    return -1;
+
+  const uint32_t our_handle = active_task - tasks + 1;
+  struct ipc_pipe *pipe = get_existing_pipe(sender_handle, our_handle);
+  if (!pipe)
+    return 0;
+
+  unwait(tasks + sender_handle - 1, (struct wait){.mode = IPC_SEND, .task = active_task});
+
+  //TODO
+}
+
+void add_wait(struct wait wait) {
+  for (uint8_t i = 0; i < MAX_WAITS; ++i)
+    if (!active_task->waits[i].mode) {
+      active_task->waits[i] = wait;
+      active_task->waiting = true;
+      return;
+    }
+  PANIC("Out of waits for task.");
+}
+
+void unwait_any(struct wait wait) {
+  for (uint8_t i = 0; i < MAX_TASKS; ++i)
+    if (tasks[i].page_directory)
+      unwait(tasks + i, wait);
+}
+
+void unwait(struct task_state *task, struct wait wait) {
+  if (!task->waiting)
+    return;
+  for (uint8_t i = 0; i < MAX_WAITS; ++i) {
+    if (task->waits[i].mode != wait.mode)
+      continue;
+    switch (wait.mode) {
+    case PROCESS_END:
+    case IPC_RECEIVE:
+      if (task->waits[i].task != wait.task)
+        continue;
+      break;
+    case WINDOW_ACTION:
+    case IPC_RECEIVE_ANY:
+      break;
+    default:
+      PANIC("Unwait matched with unrecognized wait mode.");
+    }
+    for (uint8_t i = 0; i < MAX_WAITS; ++i)
+      task->waits[i].mode = NONE;
+    task->waiting = false;
+    return;
+  }
 }
\ No newline at end of file