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ASSEMBLY & COMPILE TOOLS/PLM VAX COMPILER/util86/unwind.mar

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+        .TITLE  UNWINDTOFRAME.S  Unwind to specified stack frame.
+;-----------------------------------------------------------------------
+;
+;               D I S C L A I M E R   N O T I C E
+;               -------------------   -----------
+;
+;  This document and/or portions of the material and data furnished
+;  herewith, was developed under sponsorship of the U. S. Government.
+;  Neither the U.S. nor the U.S.D.O.E., nor the Leland Stanford Junior
+;  University, nor their employees, nor their respective contractors,
+;  subcontractors, or their employees, makes any warranty, express or
+;  implied, or assumes any liability or responsibility for accuracy,
+;  completeness or usefulness of any information, apparatus, product
+;  or process disclosed, or represents that its use will not infringe
+;  privately-owned rights.  Mention of any product, its manufacturer,
+;  or suppliers shall not, nor is it intended to, imply approval, dis-
+;  approval, or fitness for any particular use.  The U. S. and the
+;  University at all times retain the right to use and disseminate same
+;  for any purpose whatsoever.  Such distribution shall be made by the
+;  National Energy Software Center at the Argonne National Laboratory
+;  and only subject to the distributee furnishing satisfactory proof
+;  that he has a valid license from the Intel Corporation in effect.
+;
+;-----------------------------------------------------------------------
+;
+;	WARNING	WARNING	WARNING	WARNING	WARNING	WARNING	WARNING
+;
+;       This code will only work for modules compiled under the
+;	SMALL or MEDIUM controls.
+;
+;-----------------------------------------------------------------------
+ 
+        .PSECT  UTIL_CODE,RD,NOWRT,EXE,GBL,CON,LONG
+ 
+	.ENTRY	UNWINDTOFRAME,^M<>
+ 
+	MOVL	4(AP),R0	; Save desired frame ptr value.
+	MOVL	16(FP),R1	; Save return address.
+LOOP:   MOVAB   B^RET1,16(FP)   ; Stuff local return addr as saved PC.
+	RET			; Pop off a stack frame.
+RET1:				; RET returns control to here.
+	CMPW	FP,R0		; Compare desired FP (low 16 bits only).
+	BNEQ	LOOP		; Pop frames until desired frame reached.
+	SUBL2	#8,R10		; -- Will get added back upon return.
+	JMP	(R1)		; Done: return to caller.
+ 
+	.END