Driving model: ThrobRevsNoTorque

       Name: ThrobRevsNoTorque                                       [Show more]
       Type: Subroutine
   Category: Driving model
    Summary: Set the rev counter after adding a random throb and zero the
             engine torque
  Deep dive: Modelling the engine
    Context: See this subroutine in context in the source code
 References: This subroutine is called as follows:
             * CalcRevsNoTorque calls ThrobRevsNoTorque
             * ProcessEngineStart calls ThrobRevsNoTorque


 Set the following:

   * revCount = A + rand(0-7)

   * revsOnGearChange = revCount

   * engineTorque = 0

   * soundRevTarget = revTarget + 25


.ThrobRevsNoTorque

 STA T                  \ Store A in T

 LDA VIA+&68            \ Read 6522 User VIA T1C-L timer 2 low-order counter
                        \ (SHEILA &68), which decrements one million times a
                        \ second and will therefore be pretty random

 AND #7                 \ Set A = A mod 8, which is a random number in the range
                        \ 0 to 7

 CLC                    \ Set A = A + T
 ADC T                  \       = random 0-7 + T

                        \ Fall through into SetRevsNoTorque to set the rev
                        \ counter to A and zero the engine torque