initial commit of lk (little kernel) project
diff --git a/arch/arm/asm.S b/arch/arm/asm.S
new file mode 100644
index 0000000..2953bd6
--- /dev/null
+++ b/arch/arm/asm.S
@@ -0,0 +1,88 @@
+/*
+ * Copyright (c) 2008 Travis Geiselbrecht
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files
+ * (the "Software"), to deal in the Software without restriction,
+ * including without limitation the rights to use, copy, modify, merge,
+ * publish, distribute, sublicense, and/or sell copies of the Software,
+ * and to permit persons to whom the Software is furnished to do so,
+ * subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+ * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+ * CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+ * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+#include <asm.h>
+
+
+ /* context switch frame is as follows:
+ * ulr
+ * usp
+ * lr
+ * r11
+ * r10
+ * r9
+ * r8
+ * r7
+ * r6
+ * r5
+ * r4
+ */
+/* arm_context_switch(addr_t *old_sp, addr_t new_sp) */
+FUNCTION(arm_context_switch)
+ /* save all the usual registers + user regs */
+ /* the spsr is saved and restored in the iframe by exceptions.S */
+ sub r3, sp, #(11*4) /* can't use sp in user mode stm */
+ mov r12, lr
+ stmia r3, { r4-r11, r12, r13, r14 }^
+
+ /* save old sp */
+ str r3, [r0]
+
+ /* load new regs */
+ ldmia r1, { r4-r11, r12, r13, r14 }^
+ mov lr, r12 /* restore lr */
+ add sp, r1, #(11*4) /* restore sp */
+ bx lr
+
+FUNCTION(arm_save_mode_regs)
+ mrs r1, cpsr
+
+#if ARM_ISA_ARMv6
+ cps #0x11 /* fiq */
+ str r13, [r0], #4
+ str r14, [r0], #4
+ cps #0x12 /* irq */
+ str r13, [r0], #4
+ str r14, [r0], #4
+ cps #0x13 /* svc */
+ str r13, [r0], #4
+ str r14, [r0], #4
+ cps #0x17 /* abt */
+ str r13, [r0], #4
+ str r14, [r0], #4
+ cps #0x1b /* und */
+ str r13, [r0], #4
+ str r14, [r0], #4
+ cps #0x1f /* sys */
+ str r13, [r0], #4
+ str r14, [r0], #4
+#else
+ // XXX implement
+ b .
+#endif
+
+ msr cpsr, r1
+
+ bx lr
+
+
+