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diff --git a/unix/as.linux64/zsvjmp.s b/unix/as.linux64/zsvjmp.s
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+++ b/unix/as.linux64/zsvjmp.s
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+	.file	"zsvjmp.s"
+
+# ZSVJMP, ZDOJMP -- Set up a jump (non-local goto) by saving the processor
+# registers in the buffer jmpbuf.  A subsequent call to ZDOJMP restores
+# the registers, effecting a call in the context of the procedure which
+# originally called ZSVJMP, but with the new status code.  These are Fortran
+# callable procedures.
+#
+#		zsvjmp (jmp_buf, status)	# (returns status)
+#		zdojmp (jmp_buf, status)	# (passes status to zsvjmp)
+#
+# These routines are directly comparable to the UNIX setjmp/longjmp, except
+# that they are Fortran callable kernel routines, i.e., trailing underscore,
+# call by reference, and no function returns.  ZSVJMP requires an assembler
+# jacket routine to avoid modifying the call stack, but relies upon setjmp
+# to do the real work.  ZDOJMP is implemented as a portable C routine in OS,
+# calling longjmp to do the restore.  In these routines, JMP_BUF consists
+# of one longword containing the address of the STATUS variable, followed
+# by the "jmp_buf" used by setjmp/longjmp.
+#
+# This file contains the FreeBSD (x86) version of ZSVJMP.
+# Modified to remove leading underscore for ELF (Jan99).
+ 
+        #.globl	_zsvjmp_
+        .globl	zsvjmp_
+
+	# The following has nothing to do with ZSVJMP, and is included here
+	# only because this assembler module is loaded with every process.
+	# This code sets the value of the symbol MEM (the VOS or Fortran Mem
+	# common) to zero, setting the origin for IRAF pointers to zero
+	# rather than some arbitrary value, and ensuring that the MEM common
+	# is aligned for all datatypes as well as page aligned.  A further
+	# advantage is that references to NULL pointers are likely to cause a
+	# memory violation.
+
+	#.globl	mem_
+	#mem_	=	0
+	.globl	_mem_
+	_mem_	=	0
+
+zsvjmp_:
+	# %rsi ... &status  %rdi ... &jumpbuf
+	movq    %rsi, (%rdi)    # store &status in jmpbuf[0]
+	movl    $0, (%rsi)      # zero the value of status
+	addq    $8, %rdi        # change point to &jmpbuf[1]
+	movl    $0, %esi        # change arg2 to zero
+	jmp     __sigsetjmp     # let sigsetjmp do the rest
+