do not use nonexistent neg_fw insn

diff --git a/detpic/mascan.asm b/detpic/mascan.asm
index 159650d96ad1d2558b755b0342264a832f94b5b9..f1b783aa5a85cd6a343a22b25f1391cb8d55b602 100644 (file)
--- a/detpic/mascan.asm
+++ b/detpic/mascan.asm
@@ -221,8 +221,8 @@ nextslave_nowrite
        return  ; do not scan while booster PWM is off while polarising
                ; to avoid all trains disappearing and reappearing
 
-       neg_fw  outmsg_begin
-       add_wfw outmsg_end
+       mov_fw  outmsg_begin
+       sub_wfw outmsg_end
        and_lw  outbuf_size - 1
        cmp_fw_ifle outmsg_targetlen
        return ; target len < actual len, do not add anything