From 980bf8921aaa568ea6bf73631eff7506d68fd2b9 Mon Sep 17 00:00:00 2001
From: David Given <dg@cowlark.com>
Date: Mon, 29 Jun 2015 00:01:25 +0200
Subject: [PATCH] Fix syscall interface and file header to actually work.

---
 Library/libs/crt0_msp430x.s         | 10 +++++-----
 Library/libs/fuzixmsp430x/syscall.s |  6 +++---
 Library/tools/syscall_msp430x.c     |  8 ++++++++
 3 files changed, 16 insertions(+), 8 deletions(-)

diff --git a/Library/libs/crt0_msp430x.s b/Library/libs/crt0_msp430x.s
index 4d3bfa37..d90e03d8 100644
--- a/Library/libs/crt0_msp430x.s
+++ b/Library/libs/crt0_msp430x.s
@@ -2,16 +2,16 @@
 .globl _start
 _start:
 	jmp 1f                             ; two bytes
-	.byte 0                            ; one byte of padding
+	.byte 0                            ; two bytes of padding
 	.byte 'F', 'Z', 'X', '1'           ; magic starts at 0x8003
 
-	.word 0 ; chmem
+	.byte 0x80                         ; page to start at
+	.word 0                            ; chmem (0 means 'all')
 	.word __data_start
-	.word __data_end
-	.word __bss_end
+	.word __data_len
+	.word __bss_len
 	.word 0 ; spare
 
-	.align 2
 1:
 	; Wipe BSS.
 	mov #__bss_start, r12
diff --git a/Library/libs/fuzixmsp430x/syscall.s b/Library/libs/fuzixmsp430x/syscall.s
index 2f2b7894..6fbb0fd2 100644
--- a/Library/libs/fuzixmsp430x/syscall.s
+++ b/Library/libs/fuzixmsp430x/syscall.s
@@ -5,11 +5,11 @@ _syscall:
         ; On entry, the syscall number is in r11 and the four parameters in
         ; r12-r15 (luckily, these are all caller saved).
         calla &(_start-4)
-        ; On exit from the kernel, the result in r12 is either 0 or an errno.
-        tst r12
+        ; On exit from the kernel, the result is in r12 and r13 is an errno.
+        tst r13
         jz 1f
 		; Error path.
-        mov r12, &errno
+        mov r13, &errno
         mov #-1, r12
 1:
         ret
diff --git a/Library/tools/syscall_msp430x.c b/Library/tools/syscall_msp430x.c
index 9d7289c2..b229f71b 100644
--- a/Library/tools/syscall_msp430x.c
+++ b/Library/tools/syscall_msp430x.c
@@ -22,6 +22,14 @@ static void write_call(int n)
 	      "\t.globl _syscall\n"
 	      "\t.globl %1$s\n\n"
 	      "%1$s:\n", syscall_name[n]);
+  if (syscall_args[n] == VARARGS)
+  {
+	/* Varargs syscalls have the first argument in r12 and the others on
+	 * the stack. We support up to four parameters. */
+	fprintf(fp, "\tmov 2(sp), r13\n"
+	            "\tmov 4(sp), r14\n"
+				"\tmov 6(sp), r15\n");
+  }
   fprintf(fp, "\tmov #%d, r11\n"
               "\tbr #_syscall\n",
 			  n);
-- 
2.34.1