Speed optimization (framebuffer scrolling)

[richard]

try some asm

untested but should be close
bcnt var byte bank 1
dcnt var byte bank 1
dspbuff var byte[380] ;36 displays + 2 outside of display * 10

rotate_r:  ' pic18
asm
    banksel _bcnt    ;ROW
    movlw   10       ;10 rows  
    movwf   _bcnt
    clrf    FSR0H
    movlw   low  (_dspbuff)
    movwf   FSR0L
    movlw   111        ;BUFFER SIZE low byte  (380-1) 36 displays + 2 outside of display * 10-1
    ADDWF   FSR0L,F
    movlw   high (_dspbuff)
    ADDWFC   FSR0H
    movlw   1        ;BUFFER SIZE high byte  (380)
    ADDWF   FSR0H
    banksel _bcnt     ;note place bcnt and dcnt in same bank
    MOVLW 38     ;36 displays + 2 outside of display  
NROW       
    movwf   _dcnt
    bcf    STATUS, C
Ncol
    rrcf   POSTDEC0 ,f     ;PER COLUMN
    DECFSZ  _dcnt ,F
    BRA    Ncol
    BNC    NBNC
    bsf    PLUSW0,7     ;max displays would be 127 to use plusw
NBNC 
    DECFSZ  _bcnt ,F
    BRA    NROW
    banksel 0
endasm

this is my 4 panel code for reference

rotate: ;pic18
asm
    banksel _bcnt    ;ROW
    movlw   8
    movwf   _bcnt
    clrf    FSR0H
    movlw   low  (_dspbuff)
    movwf   FSR0L
    movlw   31        ;BUFFER SIZE
    ADDWF   FSR0L,F
    movlw   high (_dspbuff)
    ADDWFC   FSR0H
    banksel _bcnt
    MOVLW 4
NROW     
    bcf    STATUS, C
    rrcf   POSTDEC0 ,f     ;PER COLUMN
    rrcf   POSTDEC0 ,f     ;PER COLUMN
    rrcf   POSTDEC0 ,f     ;PER COLUMN
    rrcf   POSTDEC0 ,f     ;PER COLUMN
    BNC    NBNC
    bsf    PLUSW0,7
NBNC 
    DECFSZ  _bcnt ,F
    BRA    NROW
endasm