POWERED_FLIGHT_SUBROUTINES.agc
### FILE="Main.annotation"
## Copyright: Public domain.
## Filename: POWERED_FLIGHT_SUBROUTINES.agc
## Purpose: A section of Luminary 1C, revision 131.
## It is part of the source code for the Lunar Module's (LM)
## Apollo Guidance Computer (AGC) for Apollo 13.
## This file is intended to be a faithful transcription, except
## that the code format has been changed to conform to the
## requirements of the yaYUL assembler rather than the
## original YUL assembler.
## Reference: pp. 1251-1259
## Contact: Ron Burkey <info@sandroid.org>.
## Website: www.ibiblio.org/apollo/index.html
## Mod history: 06/03/03 RSB. Began transcribing.
## 05/14/05 RSB Corrected website reference above.
## 2010-10-25 JL Indentation fixes.
## 2017-01-06 RSB Page numbers now agree with those on the
## original hardcopy, as opposed to the PDF page
## numbers in 1701.pdf.
## 2017-02-27 RSB Proofed comment text using octopus/ProoferComments.
## 2017-03-01 RSB Fixed lingering comment-text typos.
## 2017-03-14 RSB Comment-text fixes noted in proofing Luminary 116.
## 2017-03-16 RSB Comment-text fixes identified in 5-way
## side-by-side diff of Luminary 69/99/116/131/210.
## 2017-03-17 RSB Comment-text fixes identified in diff'ing
## Luminary 99 vs Comanche 55.
## 2021-05-30 ABS SINSLOC -> SINESLOC
## Page 1251
BANK 14 # SAME FBANK AS THE FINDCDUD SUB-PROGRAM
SETLOC POWFLITE
BANK
EBANK= DEXDEX
COUNT* $$/POWFL
# CDUTRIG, CDUTRIG1, CDUTRIG2, AND CD*TR*GS ALL COMPUTE THE SINES AND
# COSINES OF THREE 2'S COMPLEMENT ANGLES AND PLACE THE RESULT, DOUBLE
# PRECISION, IN THE SAME ORDER AS THE INPUTS, AT SINCDU AND COSCDU. AN
# ADDITIONAL OUTPUT IS THE 1'S COMPLEMENT ANGLES AT CDUSPOT. THESE
# ROUTINES GO OUT OF THEIR WAY TO LEAVE THE MPAC AREA AS THEY FIND IT,
# EXCEPT FOR THE GENERALLY UNIMPORTANT MPAC +2. THEY DIFFER ONLY IN
# WHERE THEY GET THE ANGLES, AND IN METHOD OF CALLING.
#
# CDUTRIG (AND CDUTRIG1, WHICH CAN BE CALLED IN BASIC) COMPUTE THE
# SINES AND COSINES FROM THE CURRENT CONTENTS OF THE CDU REGISTERS.
# THE CONTENTS OF CDUTEMP, ETC., ARE NOT TOUCHED SO THAT THEY MAY
# CONTINUE TO FORM A CONSISTENT SET WITH THE LATEST PIPA READINGS.
#
# CDUTRIG1 IS LIKE CDUTRIG EXCEPT THAT IT CAN BE CALLED IN BASIC.
#
# CD*TR*GS FINDS CDU VALUES IN CDUSPOT RATHER THAN IN CDUTEMP. THIS
# ALLOWS USERS TO MAKE TRANSFORMATIONS USING ARBITRARY ANGLES, OR REAL
# ANGLES IN AN ORDER OTHER THAN X Y Z. A CALL TO THIS ROUTINE IS
# NECESSARY IN PREPARATION FOR A CALL TO AX*SR*T IN EITHER OF ITS TWO
# MODES (SMNB OR NBSM). SINCE AX*SR*T EXPECTS TO FIND THE SINES AND
# COSINES IN THE ORDER Y Z X THE ANGLES MUST HAVE BEEN PLACED IN CDUSPOT
# IN THIS ORDER. CD*TR*GS NEED NOT BE REPEATED WHEN AX*SR*T IS CALLED
# MORE THAN ONCE, PROVIDED THE ANGLES HAVE NOT CHANGED. NOTE THAT SINCE
# IT CLOBBERS BUF2 (IN THE SINE AND COSINE ROUTINES) CD*TR*GS CANNOT BE
# CALLED USING BANKCALL. SORRY.
#
# CD*TR*G IS LIKE CD*TR*GS EXCEPT THAT IT CAN BE CALLED IN
# INTERPRETIVE.
CDUTRIG EXIT
TC CDUTRIGS
TC INTPRET
RVQ
CD*TR*G EXIT
TC CD*TR*GS
TC INTPRET
RVQ
CDUTRIGS CA CDUX
TS CDUSPOT +4
CA CDUY
TS CDUSPOT
## Page 1252
CA CDUZ
TS CDUSPOT +2
CD*TR*GS EXTEND
QXCH TEM2
CAF FOUR
TR*GL**P MASK SIX # MAKE IT EVEN AND SMALLER
TS TEM3
INDEX TEM3
CA CDUSPOT
DXCH MPAC # STORING 2'S COMP ANGLE, LOADING MPAC
DXCH VBUF +4 # STORING MPAC FOR LATER RESTORATION
TC USPRCADR
CADR CDULOGIC
EXTEND
DCA MPAC
INDEX TEM3
DXCH CDUSPOT # STORING 1'S COMPLEMENT ANGLE
TC USPRCADR
CADR COSINE
DXCH MPAC
INDEX TEM3
DXCH COSCDU # STORING COSINE
EXTEND
INDEX TEM3
DCA CDUSPOT # LOADING 1'S COMPLEMENT ANGLE
TC USPRCADR
CADR SINE +1 # SINE +1 EXPECTS ARGUMENT IN A AND L
DXCH VBUF +4 # BRINGING UP PRIOR MPAC TO BE RESTORED
DXCH MPAC
INDEX TEM3
DXCH SINCDU
CCS TEM3
TCF TR*GL**P
TC TEM2
## Page 1253
# ****************************************************************************************************************
# QUICTRIG, INTENDED FOR GUIDANCE CYCLE USE WHERE TIME IS CRITICAL, IS A MUCH FASTER VERSION OF CD*TR*GS.
# QUICTRIG COMPUTES AND STORES THE SINES AND COSINES OF THE 2'S COMPLEMENT ANGLES AT CDUSPOT, CDUSPOT +2,
# AND CDUSPOT +4. UNLIKE CD*TR*GS, QUICTRIG DOES NOT LEAVE THE 1'S COMPLEMENT VERSIONS OF THE ANGLES IN
# CDUSPOT. QUICTRIG'S EXECUTION TIME IS 4.1 MS; THIS IS 10 TIMES AS FAST AS CD*TR*GS. QUICTRIG MAY BE
# CALLED FROM INTERPRETIVE AS AN RTB OP-CODE, OR FROM BASIC VIA BANKCALL OR IBNKCALL.
QUICTRIG INHINT # INHINT SINCE DAP USES THE SAME TEMPS
EXTEND
QXCH ITEMP1
CAF FOUR
+4 MASK SIX
TS ITEMP2
INDEX ITEMP2
CA CDUSPOT
TC SPSIN
EXTEND
MP BIT14 # SCALE DOWN TO MATCH INTERPRETER OUTPUTS
INDEX ITEMP2
DXCH SINCDU
INDEX ITEMP2
CA CDUSPOT
TC SPCOS
EXTEND
MP BIT14
INDEX ITEMP2
DXCH COSCDU
CCS ITEMP2
TCF QUICTRIG +4
CA ITEMP1
RELINT
TC A
## Page 1254
# ****************************************************************************************************************
# THESE INTERFACE ROUTINES MAKE IT POSSIBLE TO CALL AX*SR*T, ETC., IN
# INTERPRETIVE. LATER, WHERE POSSIBLE, THEY WILL BE ELIMINATED.
#
# THESE INTERFACE ROUTINES ARE PERMANENT. ALL RESTORE USER'S EBANK
# SETTING. ALL ARE STRICT INTERPRETIVE SUBROUTINES, CALLED USING "CALL",
# RETURNING VIA QPRET. ALL EXPECT AND RETURN THE VECTOR TO BE TRANSFOR-
# MED INTERPRETER-STYLE IN MPAC; COMPONENTS AT MPAC, MPAC +3, AND MPAC +5.
#
# TRG*SMNB AND TRG*NBSM BOTH EXPECT TO SEE THE 2'S COMPLEMENT ANGLES
# AT CDUSPOT (ORDER Y Z X, AT CDUSPOT, CDUSPOT +2, AND CDUSPOT +4; ODD
# LOCATIONS NEED NOT BE ZEROED). TRG*NBSM DOES THE NB TO SM TRANSFOR-
# MATION; TRG*SMNB, VICE VERSA.
#
# CDU*NBSM DOES ITS TRANSFORMATION USING THE PRESENT CONTENTS OF
# THE CDU COUNTERS. OTHERWISE IT IS LIKE TRG*NBSM.
#
# CDU*SMNB IS THE COMPLEMENT OF CDU*NBSM.
CDU*SMNB EXIT
TC CDUTRIGS
TCF C*MM*N1
TRG*SMNB EXIT
TC CD*TR*GS
C*MM*N1 TC MPACVBUF # AX*SR*T EXPECTS VECTOR IN VBUF
CS THREE # SIGNAL FOR SM TO NB TRANSFORMATION
C*MM*N2 TC AX*SR*T
TC INTPRET
VLOAD RVQ
VBUF
CDU*NBSM EXIT
TC CDUTRIGS
TCF C*MM*N3
TRG*NBSM EXIT
TC CD*TR*GS
C*MM*N3 TC MPACVBUF # FOR AX*SR*T
CA THREE # SIGNAL FOR NB TO SM TRANSFORMATION
TCF C*MM*N2
# *NBSM* AND *SMNB* EXPECT TO SEE THE SINES AND COSINES (AT SINCDU
# AND COSCDU) RATHER THAN THE ANGLES THEMSELVES. OTHERWISE THEY ARE
# LIKE TRG*NBSM AND TRG*SMNB.
#
# NOTE THAT JUST AS CD*TR*GS NEED BE CALLED ONLY ONCE FOR EACH SERIES
# OF TRANSFORMATIONS USING THE SAME ANGLES, SO TOO ONLY ONE OF TRG*NBSM
## Page 1255
# AND TRG*SMNB NEED BE CALLED FOR EACH SERIES. FOR SUBSEQUENT TRANSFOR-
# MATIONS USE *NBSM* AND *SMNB*.
*SMNB* EXIT
TCF C*MM*N1
*NBSM* EXIT
TCF C*MM*N3
# AX*SR*T COMBINES THE OLD SMNB AND NBSM. FOR THE NB TO SM
# TRANSFORMATION, ENTER WITH +3 IN A. FOR SM TO NB, ENTER WITH -3.
# THE VECTOR TO BE TRANSFORMED ARRIVES, AND IS RETURNED, IN VBUF.
# AX*SR*T EXPECTS TO FIND THE SINES AND COSINES OF THE ANGLES OF ROTATION
# AT SINCDU AND COSCDU, IN THE ORDER Y Z X. A CALL TO CD*TR*GS, WITH
# THE 2'S COMPLEMENT ANGLES (ORDER Y Z X) AT CDUSPOT, WILL TAKE CARE OF
# THIS. HERE IS A SAMPLE CALLING SEQUENCE:-
# TC CDUTRIGS
# CS THREE ("CA THREE" FOR NBSM)
# TC AX*SR*T
# THE CALL TO CD*TR*GS NEED NOT BE REPEATED, WHEN AX*SR*T IS CALLED MORE
# THAN ONCE, UNLESS THE ANGLES HAVE CHANGED.
#
# AX*SR*T IS GUARANTEED SAFE ONLY FOR VECTORS OF MAGNITUDE LESS THAN
# UNITY. A LOOK AT THE CASE IN WHICH A VECTOR OF GREATER MAGNITUDE
# HAPPENS TO LIE ALONG AN AXIS OF THE SYSTEM TO WHICH IT IS TO BE TRANS-
# FORMED CONVINCES ONE THAT THIS IS A RESTRICTION WHICH MUST BE ACCEPTED.
AX*SR*T TS DEXDEX # WHERE IT BECOMES THE INDEX OF INDEXES
EXTEND
QXCH RTNSAVER
R*TL**P CCS DEXDEX # +3 --> 0 -3 --> 2
CS DEXDEX # THUS: +2 --> 1 -2 --> 1
AD THREE # +1 --> 2 -1 --> 0
EXTEND
INDEX A
DCA INDEXI
DXCH DEXI
CA ONE
TS BUF
EXTEND
INDEX DEX1
DCS VBUF
TCF LOOP1 # REALLY BE A SUBTRACT, AND VICE VERSA
LOOP2 DXCH BUF # LOADING VECTOR COMPONENT, STORING INDEX
## Page 1256
LOOP1 DXCH MPAC
CA SINESLOC
AD DEX1
TS ADDRWD
TC DMPSUB # MULTIPLY BY SIN(CDUANGLE)
CCS DEXDEX
DXCH MPAC # NBSM CASE
TCF +3
EXTEND # SMNB CASE
DCS MPAC
DXCH TERM1TMP
CA SIX # SINCDU AND COSCDU (EACH 6 WORDS) MUST
ADS ADDRWD # BE CONSECUTIVE AND IN THAT ORDER
EXTEND
INDEX BUF
INDEX DEX1
DCA VBUF
DXCH MPAC
TC DMPSUB # MULTIPLY BY COS(CDUANGLE)
DXCH MPAC
DAS TERM1TMP
DXCH TERM1TMP
DDOUBL
INDEX BUF
INDEX DEX1
DXCH VBUF
DXCH BUF # LOADING INDEX, STORING VECTOR COMPONENT
CCS A # 'CAUSE THAT'S WHERE THE INDEX NOW IS
TCF LOOP2
EXTEND
DIM DEXDEX # DECREMENT MAGNITUDE PRESERVING SIGN
TSTPOINT CCS DEXDEX # ONLY THE BRANCHING FUNCTION IS USED
TCF R*TL**P
TC RTNSAVER
TCF R*TL**P
TC RTNSAVER
SINESLOC ADRES SINCDU # FOR USE IN SETTING ADDRWD
INDEXI DEC 4 # ********** DON'T **********
DEC 2 # ********** TOUCH **********
DEC 0 # ********** THESE **********
## Page 1257
DEC 4 # ********** CONSTANTS **********
# ****************************************************************************************************************
BANK 10
SETLOC FLESHLOC
BANK
COUNT* $$/POWFL
# ROUTINE FLESHPOT COMPUTES THE BODY-STABLE MEMBER TRANSFORMATION MATRIX (COMMONLY CALLED XNB) AND STORES
# IT IN THE LOCATIONS SPECIFIED BY THE ECADR ENTERING IN A.
CALCSMSC EXIT
TC BANKCALL
CADR FLESHPOT -1
TC INTPRET
RVQ
XNBECADR ECADR XNB
-1 CAF XNBECADR
FLESHPOT TS TEM2
XCH EBANK
XCH TEM2
MASK LOW8
AD OCT1400
TS TEM1
EXTEND
DCA COSCDUY
DXCH MPAC
TC DMP
ADRES COSCDUZ
DXCH MPAC
DDOUBL
INDEX TEM1
DXCH 0 # = COSY COSZ
EXTEND
DCA SINCDUZ
INDEX TEM1
DXCH 2 # = SINZ
EXTEND
DCS SINCDUY
DXCH MPAC
TC DMPSUB # ADDRWD SET TO COSCDUZ
## Page 1258
DXCH MPAC
DDOUBL
INDEX TEM1
DXCH 4 # = - SINY COSZ
EXTEND
DCS SINCDUX
DXCH MPAC
TC DMPSUB # ADDRWD SET TO COSCDUZ STILL
DXCH MPAC
DDOUBL
DXCH MPAC +3
EXTEND
DCS SINCDUX
DXCH MPAC
TC DMP
ADRES SINCDUZ
EXTEND
DCS MPAC
DXCH MPAC +5
TC DMP
ADRES SINCDUY
DXCH MPAC
DDOUBL
DDOUBL
DXCH MPAC +5
DXCH MPAC
TC DMP
ADRES COSCDUY
DXCH MPAC
DDOUBL
DDOUBL
DXCH BUF
EXTEND
DCA COSCDUY
DXCH MPAC
TC DMP
ADRES COSCDUX
DXCH MPAC
DDOUBL
DAS MPAC +5
EXTEND
DCA SINCDUY
DXCH MPAC
TC DMPSUB # ADDRWD SET TO COSCDUX
DXCH MPAC
## Page 1259
DDOUBL
DAS BUF
DXCH BUF
DXCH MPAC
EXTEND
DCA MPAC
INDEX TEM1
DXCH 14 # = SINY COSX + SINX SINZ COSY
EXTEND
DCA MPAC +3
INDEX TEM1
DXCH 16 # = - SINX COSZ
EXTEND
DCA MPAC +5
INDEX TEM1
DXCH 20 # = COSX COSY - SINX SINY SINZ
CA TEM1
TS ADDRWD
EXTEND
DCA Z
AD FOUR
DXCH LOC
CAF BIT8
TS EDOP
TCF VXV
DXCH MPAC
DDOUBL
INDEX TEM1
DXCH 6
DXCH MPAC +3
DDOUBL
INDEX TEM1
DXCH 10
DXCH MPAC +5
DDOUBL
INDEX TEM1
DXCH 12
CA TEM2
TS EBANK
TCF SWRETURN
