lib: Add bossac 1.9 code to lib directory

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

lib/bossac/src/WordCopyArm.asm

@@ -0,0 +1,47 @@
+    .global start
+    .global stack
+    .global reset
+    .global dst_addr
+    .global src_addr
+    .global words
+
+    .text
+    .thumb
+    .align 0
+
+start:
+    ldr     r0, dst_addr
+    ldr     r1, src_addr
+    ldr     r2, words
+    b       check
+    
+copy:
+    ldmia   r1!, {r3}
+    stmia   r0!, {r3}
+    sub     r2, #1
+    
+check:
+    cmp     r2, #0
+    bne     copy
+    
+    @ Fix for SAM-BA stack bug
+    ldr     r0, reset
+    cmp     r0, #0
+    bne     return
+    ldr     r0, stack
+    mov     sp, r0
+
+return:
+    bx      lr
+
+    .align  0
+stack:
+    .word   0
+reset:
+    .word   0
+dst_addr:
+    .word   0
+src_addr:
+    .word   0
+words:
+    .word   0