Update environment

sys/core.s

@@ -0,0 +1,38 @@
+# file:    core.s
+# project: Löwe OS
+# authors: Elias Löwe <elias@lowenware.com>
+
+# -----------------------------------------------------------------------------
+
+  .global _core_init
+  .extern _uart_puts
+
+# -----------------------------------------------------------------------------
+
+  .text
+
+_core_init:
+  # set up stack pointer using x30 register
+  LDR     x30, =0x40001000
+  MOV     sp,  x30
+  bl      1f
+
+1:
+  LDR     x0,  =some_int
+  BL      _uart_putx
+  LDR     x0,  =greeting
+  BL      _uart_puts
+2:
+  B       2b
+
+# -----------------------------------------------------------------------------
+
+  .data
+
+greeting:
+  .asciz "\nStarting Lowe OS\n"
+
+
+  .equ some_int, 0x1234567890ABCDEF
+
+# -----------------------------------------------------------------------------

sys/main.c

@@ -0,0 +1,37 @@
+/******************************************************************************
+ *
+ *                Copyright (c) 2017-2019 by Löwenware Ltd
+ *             Please, refer LICENSE file for legal information
+ *
+ ******************************************************************************/
+
+/**
+ * @file main.c
+ * @author Ilja Kartašov <ik@lowenware.com>
+ * @brief 
+ *
+ * @see https://lowenware.com/
+ */
+
+#include "uart.h"
+
+
+void
+k_main(void);
+
+
+void
+k_main(void)
+{
+	uart_init();
+
+	uart_putc('L');
+	uart_putc('o');
+	uart_putc('w');
+	uart_putc('e');
+	uart_putc('\n');
+
+	for (;;) {
+	}
+}
+

sys/memmap

@@ -0,0 +1,12 @@
+    ENTRY(_start)
+
+    SECTIONS
+    {
+      . = 0x40000000;
+      .text : { *(.text) }
+      .data : { *(.data) }
+      .bss : { *(.bss COMMON) }
+      . = ALIGN(8);
+      . = . + 0x1000;
+      stack_ptr = . ;
+    }

sys/uart.c

@@ -0,0 +1,33 @@
+/******************************************************************************
+ *
+ *                Copyright (c) 2017-2019 by Löwenware Ltd
+ *             Please, refer LICENSE file for legal information
+ *
+ ******************************************************************************/
+
+/**
+ * @file uart.c
+ * @author Ilja Kartašov <ik@lowenware.com>
+ * @brief 
+ *
+ * @see https://lowenware.com/
+ */
+
+#include "uart.h"
+
+unsigned int *uart_base = (unsigned int *)UART_BASE;
+
+
+void
+uart_init(void)
+{
+
+}
+
+void
+uart_putc(unsigned char c)
+{
+	*uart_base = c;
+	if(c == '\n')
+		*uart_base = '\r';
+}

sys/uart.h

@@ -0,0 +1,30 @@
+/******************************************************************************
+ *
+ *                Copyright (c) 2017-2019 by Löwenware Ltd
+ *             Please, refer LICENSE file for legal information
+ *
+ ******************************************************************************/
+
+/**
+ * @file uart.h
+ * @author Ilja Kartašov <ik@lowenware.com>
+ * @brief 
+ *
+ * @see https://lowenware.com/
+ */
+
+#ifndef UART_H_8AFC47F9_2953_42C1_A5C1_1AE5A1F52CD0
+#define UART_H_8AFC47F9_2953_42C1_A5C1_1AE5A1F52CD0
+
+
+#define UART_BASE 0x09000000
+
+void
+uart_init(void);
+
+void
+uart_putc(unsigned char c);
+
+
+
+#endif /* !UART_H */

sys/uart.s

@@ -0,0 +1,93 @@
+// file    : uart.s
+// project : Löwe OS
+// authors : Elias Löwe <elias@lowenware.com>
+
+// address of UART for virt device in qemu
+
+// -----------------------------------------------------------------------------
+
+  .global _uart_putc    // print single character uart
+  .global _uart_putx    // print integer in HEX format to uart
+  .global _uart_puts    // print null-terminated string to uart
+
+// -----------------------------------------------------------------------------
+
+  .text
+
+// helper to avoid extra data moving
+// @x1 character print
+uart_putc:
+  STP     x2, lr, [sp, -16]!
+
+  MOV     x2, 0x09000000              // set UART address
+  STRB    w1, [x2]                    // put character out
+
+  LDP     x2, lr, [sp], 16
+  RET
+
+// -----------------------------------------------------------------------------
+
+
+// print character to uart
+// @x0 character print
+_uart_putc:
+  STR     lr, [sp, -16]!
+
+  MOV     x1, x0                      // set arguments
+  BL      uart_putc                   // put character out
+
+  LDR     lr, [sp], 16
+  RET
+  
+
+// -----------------------------------------------------------------------------
+
+// @x0 integer to print
+_uart_putx:
+  STP     lr, x3, [sp, -32]!
+  STP     x0, x1, [sp, 16]
+
+  LDR     x3, =60                     // init bits counter 64-4
+
+1:
+  LSR     x1, x0, x3                  // shift to digit
+  AND     x1, x1, 0xF                 // keep only digit
+  CMP     x1, 9                       // compare it to 9
+  BLS     2f                          // less or equal
+  ADD     x1, x1, 0x37                // turn into ASCII HEX char
+  B       3f                          // continue to output
+
+2:
+  ADD     x1, x1, 0x30                // turn into ASCII num char
+
+3:
+  BL      uart_putc                   // output carachter
+  CBZ     x3, 0f                      // if counter == 0 return
+  SUB     x3, x3, 4                   // otherwise subtract counter by 4
+  B       1b                          // repeat
+
+0:
+  LDP     lr, x3, [sp], 16
+  LDP     x0, x1, [sp], 16
+  RET
+
+// -----------------------------------------------------------------------------
+
+// @x0 pointer to string
+
+_uart_puts:
+  STR     lr, [sp, -16]!
+  STP     x0, x1, [sp, -16]!
+
+1:
+  LDRB    w1, [x0], 1                  // load byte of string from address in x0
+  CBZ     w1, 0f                       // return if zero
+  BL      uart_putc                    // put charcter out
+  B       1b                           // loop
+
+0:
+  LDP     x0, x1, [sp], 16
+  LDR     lr, [sp], 16
+  RET
+
+// -----------------------------------------------------------------------------