From d397ad5154fde6c5a4f4dea9bfc3227022cffe32 Mon Sep 17 00:00:00 2001
From: hidnplayr <hidnplayr@kolibrios.org>
Date: Fri, 22 May 2020 15:38:59 +0000
Subject: [PATCH] User-land ring buffers.

git-svn-id: svn://kolibrios.org@7967 a494cfbc-eb01-0410-851d-a64ba20cac60
---
 kernel/trunk/core/heap.inc     | 69 ++++++++++++++++++++++++++++++++++
 kernel/trunk/core/memory.inc   | 20 ++++++----
 kernel/trunk/docs/sysfuncs.txt | 19 ++++++++++
 3 files changed, 101 insertions(+), 7 deletions(-)

diff --git a/kernel/trunk/core/heap.inc b/kernel/trunk/core/heap.inc
index 7184e0b4e4..aa9739f083 100644
--- a/kernel/trunk/core/heap.inc
+++ b/kernel/trunk/core/heap.inc
@@ -1518,3 +1518,72 @@ proc shmem_close stdcall, name:dword
         ret
 endp
 
+
+
+proc    user_ring stdcall, size:dword
+
+locals
+        virt_ptr        dd ?
+        phys_ptr        dd ?
+        num_pages       dd ?
+endl
+
+; Size must be an exact multiple of pagesize
+        mov     eax, size
+        test    eax, PAGE_SIZE-1
+        jnz     .exit
+
+; We must have at least one complete page
+        shr     eax, 12
+        jz      .exit
+        mov     [num_pages], eax
+
+; Allocate double the virtual memory
+        mov     eax, [size]
+        shl     eax, 1
+        jz      .exit
+        stdcall user_alloc, eax
+        test    eax, eax
+        jz      .exit
+        mov     [virt_ptr], eax
+
+; Now allocate physical memory
+        stdcall alloc_pages, [num_pages]
+        test    eax, eax
+        jz      .exit_free_virt
+        mov     [phys_ptr], eax
+
+; Map first half of virtual memory to physical memory
+        push    ecx esi edi
+        mov     ecx, [num_pages]
+        mov     esi, [virt_ptr]
+        mov     edi, [phys_ptr]
+  .loop1:
+        stdcall map_page, esi, edi, PG_UWR
+        add     esi, PAGE_SIZE
+        add     edi, PAGE_SIZE
+        dec     ecx
+        jnz     .loop1
+
+; Map second half of virtual memory to same physical memory
+        mov     ecx, [pages]
+        mov     edi, [phys_ptr]
+  .loop2:
+        stdcall map_page, esi, edi, PG_UWR
+        add     esi, PAGE_SIZE
+        add     edi, PAGE_SIZE
+        dec     ecx
+        jnz     .loop2
+        pop     edi esi ecx
+
+        mov     eax, [virt_ptr]
+        ret
+
+  .exit_free_virt:
+        stdcall user_free, [virt_ptr]
+
+  .exit:
+        xor     eax, eax
+        ret
+
+endp
\ No newline at end of file
diff --git a/kernel/trunk/core/memory.inc b/kernel/trunk/core/memory.inc
index bd667fb721..075b53dc2e 100644
--- a/kernel/trunk/core/memory.inc
+++ b/kernel/trunk/core/memory.inc
@@ -1,6 +1,6 @@
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
 ;;                                                              ;;
-;; Copyright (C) KolibriOS team 2004-2015. All rights reserved. ;;
+;; Copyright (C) KolibriOS team 2004-2020. All rights reserved. ;;
 ;; Distributed under terms of the GNU General Public License    ;;
 ;;                                                              ;;
 ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
@@ -78,7 +78,7 @@ proc alloc_pages stdcall, count:dword
 .find:
         mov     edx, [count]
         mov     edi, ecx
-.match:
+  .match:
         cmp     byte [ecx], 0xFF
         jne     .next
         dec     edx
@@ -86,14 +86,14 @@ proc alloc_pages stdcall, count:dword
         inc     ecx
         cmp     ecx, ebx
         jb      .match
-.out_of_memory:
-.fail:
+  .out_of_memory:
+  .fail:
         xor     eax, eax
         pop     edi
         pop     ebx
         popfd
         ret
-.next:
+  .next:
         inc     ecx
         cmp     ecx, ebx
         jb      .find
@@ -102,7 +102,7 @@ proc alloc_pages stdcall, count:dword
         popfd
         xor     eax, eax
         ret
-.ok:
+  .ok:
         sub     ecx, edi
         inc     ecx
         push    esi
@@ -1103,7 +1103,7 @@ f68:
         jbe     sys_sheduler
         cmp     ebx, 11
         jb      undefined_syscall
-        cmp     ebx, 28
+        cmp     ebx, 29
         ja      undefined_syscall
         xor     eax, eax
         jmp     dword [f68call+ebx*4-11*4]
@@ -1220,6 +1220,11 @@ f68:
         stdcall kernel_free, ebp
         ret
 
+.29:
+        stdcall user_ring, ecx
+        mov     [esp+SYSCALL_STACK._eax], eax
+        ret
+
 .fail:
         mov     [esp+SYSCALL_STACK._eax], eax
         ret
@@ -1245,6 +1250,7 @@ f68call:   ; keep this table closer to main code
            dd f68.26   ; user_unmap
            dd f68.27   ; load_file_umode
            dd f68.28   ; loadFileUnicode
+           dd f68.29   ; user_ring
 
 align 4
 proc load_pe_driver stdcall, file:dword, cmdline:dword
diff --git a/kernel/trunk/docs/sysfuncs.txt b/kernel/trunk/docs/sysfuncs.txt
index 65914e1546..65eb6f7c35 100644
--- a/kernel/trunk/docs/sysfuncs.txt
+++ b/kernel/trunk/docs/sysfuncs.txt
@@ -3612,6 +3612,25 @@ Returned value:
   * edx = size of the loaded file, or zero
 Remarks:
   * function loads file and unpacks, if necessary
+======================================================================
+======== Function 68, subfunction 29 - allocate ring memory. =========
+======================================================================
+Parameters:
+  * eax = 68 - function number
+  * ebx = 29 - subfunction number
+  * ecx = required size in bytes
+Returned value:
+  * eax = 0 - failed
+  * eax = pointer to the allocated ring
+Remarks:
+  * The requested size must be an exact multiple of pagesize (4 Kb)
+  * The function allocates memory in such a way that you can read and
+    write beyond the size of the allocated memory and will reach the 
+    beginning of the buffer again.
+
+---------------------- Constants for registers: ----------------------
+  eax - SF_SYS_MISC (68)
+  ebx - SSF_MEM_ALLOC_RING (29)  
 
 ======================================================================
 ====================== Function 69 - debugging. ======================