Proper userspace program

kernel/include/sys/Syscall.h

@@ -6,6 +6,8 @@
 #define SYS_yield 1
 #define SYS_sleep 2
 #define SYS_write 3
+#define SYS_paint 4
+#define SYS_rand 5
 
 namespace Syscall
 {
@@ -15,4 +17,6 @@ namespace Syscall
 void sys_exit(Context* context);
 void sys_yield(Context* context);
 void sys_sleep(Context* context, uint64_t ms);
-void sys_write(Context* context, const char* addr, size_t size);
+void sys_write(Context* context, const char* addr, size_t size);
+void sys_paint(Context* context, uint64_t x, uint64_t y, uint64_t w, uint64_t h, uint64_t col);
+void sys_rand(Context* context);

kernel/src/main.asm

@@ -9,20 +9,36 @@ global _userspace
 _userspace:
     mov rdi, 4000 ; 4000 ms / 4 seconds
     mov rax, 2 ; sys_sleep
-    int 42h ; syscall
-    mov rcx, 10
-.loop:
-    dec rcx
+    int 42h
+    cmp rax, 0
+    jne .fail ; syscall failed
     mov rdi, .message
-    mov rsi, 22
+    mov rsi, 33
     mov rax, 3 ; sys_write
-    int 42h ; syscall
-    mov rdi, 200 ; 200 ms / 0.2 seconds
-    mov rax, 2
-    int 42h ; syscall
-    cmp rcx, 0
-    jne .loop
-    mov rax, 0
-    int 42h ; Exit current task
+    int 42h
+    cmp rax, 33
+    jne .fail ; syscall did not write enough bytes
+.draw:
+    mov rax, 5 ; sys_rand
+    int 42h
+    mov r9, rax ; color
+    mov rdi, 20 ; x
+    mov rsi, 20 ; y
+    mov r10, 40 ; width
+    mov r8, 30 ; height
+    mov rax, 4 ; sys_paint
+    int 42h
+    cmp rax, 0
+    jne .fail
+    mov rdi, 100
+    mov rax, 2 ; sys_sleep
+    int 42h
+    cmp rax, 0
+    jne .fail
+    jmp .draw
+.fail:
+    mov rax, 0 ; sys_exit
+    int 42h
+    jmp $ ; sys_exit failed, nothing more we can do
 .message:
-    db "hello from userspace!", 0xA, 0
+    db "userspace preparing for painting", 0xA

kernel/src/sys/Syscall.cpp

@@ -19,6 +19,8 @@ void Syscall::entry(Context* context)
     case SYS_write: // sys_write
         sys_write(context, (const char*)context->rdi, context->rsi);
         break;
+    case SYS_paint: sys_paint(context, context->rdi, context->rsi, context->r10, context->r8, context->r9); break;
+    case SYS_rand: sys_rand(context); break;
     default: context->rax = -1; break;
     }
 }

kernel/src/sys/gfx.cpp

@@ -0,0 +1,27 @@
+#include "bootboot.h"
+#include "interrupts/Context.h"
+#include "render/Framebuffer.h"
+#include <stdint.h>
+
+extern BOOTBOOT bootboot;
+
+void sys_paint(Context* context, uint64_t x, uint64_t y, uint64_t w, uint64_t h, uint64_t c)
+{
+    if ((x + w) > bootboot.fb_width)
+    {
+        context->rax = -1;
+        return;
+    }
+    if ((y + h) > bootboot.fb_height)
+    {
+        context->rax = -1;
+        return;
+    }
+
+    uint32_t color = (uint32_t)c;
+    uint32_t* colptr = &color;
+
+    framebuffer0.paint_rect(x, y, w, h, *(Color*)colptr);
+
+    context->rax = 0;
+}

kernel/src/sys/rand.cpp

@@ -0,0 +1,7 @@
+#include "interrupts/Context.h"
+#include "rand/Mersenne.h"
+
+void sys_rand(Context* context)
+{
+    context->rax = Mersenne::get();
+}