### FILE="Main.annotation"
## Copyright:   Public domain.
## Filename:    FIND_CDU_DESIRED.agc
## Purpose:     A section of Sunburst revision 37, or Shepatin revision 0.
##              It is part of an early development version of the software
##              for Apollo Guidance Computer (AGC) on the unmanned Lunar
##              Module (LM) flight Apollo 5. Sunburst 37 was the program
##              upon which Don Eyles's offline development program Shepatin
##              was based; the listing herein transcribed was actually for
##              the equivalent revision 0 of Shepatin.
##              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. 784-787
## Assembler:   yaYUL
## Contact:     Ron Burkey <info@sandroid.org>.
## Website:     www.ibiblio.org/apollo/index.html
## Mod history: 2017-05-24 MAS  Created from Sunburst 120.
##              2017-06-14 HG   Transcribed
##		2017-06-23 RSB	Proofed comment text with
##				octopus/ProoferComments.

## Page 784
# THIS ROUTINE FINDCDUD COMPUTES DESIRED CDU,S WHICH CAN BE FED TO
# DAP LATER ON.

# DESIRED CDU,S WILL BE IN 2,S COMP

# INPUT

# DESIRED THRUST VECTOR AXISD COMING FROM GUIDANCE EQUATIONS
# CDUX,CDUY,CDUZ INFORM OF A SP VECTOR CDUTEMP,+2,+4.
# DELV HALF UNIT VECTOR. PIPAS READING
# AXISD IS A HALF UNIT VECTOR
# CDUX,Y,Z  ARE IN 2,S COMP
#

# THIS ROUTINE CAN BE ENTERED FROM INTERPRETIVE . CALL FINDCDUD

# CALLING SEQUENCE
# L-1  CALL
# L        FINDCDUD
# L+1              INTERPRETIVE RETURN



# USER TO HAVE A UNIT VECTOR  AXIS   (1,0,0)



                BANK            30
                EBANK=          DELR
2/PI            2DEC            .6366198

LIMOMG          2DEC            .0001234



FINDCDUD        SETPD           EXIT
                                0
                CA              CDUTEMP         +2
                TS              SINCDU                  # TEMPORARY LOCATION FOR CDUY
                CA              CDUTEMP         +4
                TS              SINCDU          +2      # TEMPORARY LOCATION FOR CDUZ
                CA              CDUTEMP
                TS              SINCDU          +4      # TEMPORARY LOCATION FOR CDUX



# AXISFILT   COMPUTES AXIS AND CORRECTS IT FOR  QUANTIZATION ERROR AND OTH
# ER ERRORS


                EBANK=          OMEGA
                CAF             PRIO3                   # OCT  03000     SWITCH EBANK

## Page 785
                XCH             EBANK
                TS              MPAC
                CAF             ZERO
                TS              TEMX                    # SQOMEGA
                TS              TEMX            +1      # SQOMEGA  +1
                INHINT
                CAE             OMEGAP
                EXTEND

                SQUARE
                DAS             TEMX                    # SQOMEGA
                CAE             OMEGAQ
                EXTEND
                SQUARE
                DAS             TEMX                    # SQOMEGA
                CAE             OMEGAR
                EXTEND
                SQUARE
                DAS             TEMX                    # SQOMEGA

                RELINT
                XCH             MPAC
                TS              EBANK
                TC              INTPRET
                EBANK=          DELR
                STQ
                                RETSAVE
AXISFILT        DLOAD           DSU



                                TEMX                    # SQOMEGA

                                LIMOMG
                BPL             LXA,1
                                ROTANGLE
                                FIXLOC
                INCR,1          XCHX,1
                                20D
                                S1
                VLOAD
                                SINCDU                  # TEMPORARY LOCATION FOR CDUY,Z,X IN
                STORE           20D                     # SP  2,S COMP

                VLOAD           UNIT
                                DELV
                STORE           32D
                CALL
                                SMNB                    # TRANSFORM DELV FROM SM TO NB
                SETPD           VSU
                                0
                                AXIS
                VSR3            VAD
                                AXIS

## Page 786
                UNIT

                STORE           AXIS
ROTANGLE        LXA,1           INCR,1
                                FIXLOC
                                20D
                XCHX,1          VLOAD
                                S1
                                SINCDU                  # TEMPORARY LOCATION FOR CDUY,Z,X IN
                STORE           20D                     # SP  2,S COMP
                VLOAD
                                AXIS
                STORE           32D
                CALL                                    # TRANSFORM  AXIS FROM NB TO SM

                                NBSM
                SETPD           VXV
                                0
                                AXISD
                VXSC
                                2/PI
                STORE           10D                     # DTHETASM  SCALETO ONE REVOLUTION
                CALL                                    # COMPUTE SIN AND COS OF CDUS FOR
                                SINCOSCD                # LATER USE



# SMCDURES     COMPUTES CDU(GIMBAL) ANGLES FROM INCREMENTAL
# CHANGES ABOUT SM AXES.    IT REQUIRES  SM  INCREMENTAL CHANGES
# AS DP  VECTOR SCALED AT  ONE REVOLUTION(DTHETASM,+2,+4).  SIN,COS(CDUX,Y
# ,Z)   ARE IN SINCDU,+2,+4 AND COSCDU,+2,+4  RESPECTIVELY,SCALED TO 2.
# CDU INCREMENTS  ARE PLACED IN DCDU,+2,+4   SCALED TO ONE REVOLUTION



SMCDURES        DLOAD           DMP
                                10D                     # DTHETASM
                                COSCDU          +2

                PDDL            DMP
                                14D                     # DTHETASM +4
                                SINCDU          +2
                BDSU
                DDV
                                COSCDU          +4
                STORE           20D                     # DCDU
                DMP             SL1                     # SCALE
                                SINCDU          +4
                BDSU

                                12D                     # DTHETASM +2
                STODL           22D                     # DCDU +2
                                10D                     # DTHETASM
                DMP             PDDL
                                SINCDU          +2

## Page 787
                                14D                     # DTHETASM +4
                DMP             DAD
                                COSCDU          +2
                SL1                                     # SCALE
                STODL           24D                     # DCDU +4
                                22D                     # DCDU +2

                DMP             DCOMP
                                SINCDU          +4      # DCDUX =-DCDUY*SIN(CDUZ)
                SL1                                     # SCALE
                STORE           20D                     # DCDU
                VLOAD           VAD
                                20D                     # DCDU
                                CDUTEMP
                RTB
                                V1STO2S                 # SCALE FROM 1,S TO 2,S
                STORE           CDUXD
                GOTO
                                RETSAVE

#
#
# SINCOSCD    COMPUTES SIN AND COS OF CDU  AND STORES AS DP VECTORS
# SINCDU ,COSCDU
# INPUT IS CDUS AS A VECTOR CDUTEMP
# OUTPUT IS SIN AND COS OF CDU,S
# CDUS ARE AVAILABLE IN 2,S COMP
# SIN AND COS ARE SCALED TO 2
# SINCOSCD CAN BE ENTERED FROM INTERPRETIVE
#

#
#
SINCOSCD        SSP             AXT,1                   # SET X1 TO 6
                                S1                      # SET S1 TO 2
                OCT             2
                OCT             6
REPEAT1         SLOAD*          RTB
                                CDUTEMP         +6,1
                                CDULOGIC                # CONVERT CDU FROM 2,S TO 1,S.  SCALE
                STORE           CDUTEMP         +6,1    # TO ONE REVOLUTION
                SIN
                STORE           SINCDU          +6,1

                DLOAD*          COS
                                CDUTEMP         +6,1
                STORE           COSCDU          +6,1
                TIX,1           RVQ
                                REPEAT1