\ --- Mod: Code removed for Elite-A: ------------------> \.MVT3 \ \LDA K+3 \ Set S = K+3 \STA S \ \AND #%10000000 \ Set T = sign bit of K(3 2 1) \STA T \ \EOR INWK+2,X \ If x_sign has a different sign to K(3 2 1), jump to \BMI MV13 \ MV13 to process the addition as a subtraction \ \LDA K+1 \ Set K(3 2 1) = K(3 2 1) + (x_sign x_hi x_lo) \CLC \ starting with the low bytes \ADC INWK,X \STA K+1 \ \LDA K+2 \ Then the middle bytes \ADC INWK+1,X \STA K+2 \ \LDA K+3 \ And finally the high bytes \ADC INWK+2,X \ \AND #%01111111 \ Setting the sign bit of K+3 to T, the original sign \ORA T \ of K(3 2 1) \STA K+3 \ \RTS \ Return from the subroutine \ \.MV13 \ \LDA S \ Set S = |K+3| (i.e. K+3 with the sign bit cleared) \AND #%01111111 \STA S \ \LDA INWK,X \ Set K(3 2 1) = (x_sign x_hi x_lo) - K(3 2 1) \SEC \ starting with the low bytes \SBC K+1 \STA K+1 \ \LDA INWK+1,X \ Then the middle bytes \SBC K+2 \STA K+2 \ \LDA INWK+2,X \ And finally the high bytes, doing A = |x_sign| - |K+3| \AND #%01111111 \ and setting the C flag for testing below \SBC S \ \ORA #%10000000 \ Set the sign bit of K+3 to the opposite sign of T, \EOR T \ i.e. the opposite sign to the original K(3 2 1) \STA K+3 \ \BCS MV14 \ If the C flag is set, i.e. |x_sign| >= |K+3|, then \ \ the sign of K(3 2 1). In this case, we want the \ \ result to have the same sign as the largest argument, \ \ which is (x_sign x_hi x_lo), which we know has the \ \ opposite sign to K(3 2 1), and that's what we just set \ \ the sign of K(3 2 1) to... so we can jump to MV14 to \ \ return from the subroutine \ \LDA #1 \ We need to swap the sign of the result in K(3 2 1), \SBC K+1 \ which we do by calculating 0 - K(3 2 1), which we can \STA K+1 \ do with 1 - C - K(3 2 1), as we know the C flag is \ \ clear. We start with the low bytes \ \LDA #0 \ Then the middle bytes \SBC K+2 \STA K+2 \ \LDA #0 \ And finally the high bytes \SBC K+3 \ \AND #%01111111 \ Set the sign bit of K+3 to the same sign as T, \ORA T \ i.e. the same sign as the original K(3 2 1), as \STA K+3 \ that's the largest argument \ \.MV14 \ \RTS \ Return from the subroutine \ --- End of removed code ----------------------------->Name: MVT3, Removed [Show more] Type: Subroutine Category: Moving Summary: Calculate K(3 2 1) = (x_sign x_hi x_lo) + K(3 2 1)Context: See this subroutine in context in the source code References: No direct references to this subroutine in this source file
Add an INWK position coordinate - i.e. x, y or z - to K(3 2 1), like this: K(3 2 1) = (x_sign x_hi x_lo) + K(3 2 1) The INWK coordinate to add to K(3 2 1) is specified by X.
Arguments: X The coordinate to add to K(3 2 1), as follows: * If X = 0, add (x_sign x_hi x_lo) * If X = 3, add (y_sign y_hi y_lo) * If X = 6, add (z_sign z_hi z_lo)
Returns: A Contains a copy of the high byte of the result, K+3 X X is preserved