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Digital-Research-Source-Code/ASSEMBLY & COMPILE TOOLS/PLM VAX COMPILER/util86/unwind.mar
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Digital Research
2020-11-06 18:50:37 +01:00

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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