1
0
mirror of https://github.com/cc65/cc65.git synced 2024-11-17 09:07:32 +00:00
cc65/libsrc/c64/acc_chameleon_speed.s

101 lines
2.5 KiB
ArmAsm
Raw Normal View History

;
; Marco van den Heuvel, 2018-04-25
;
; unsigned char __fastcall__ set_chameleon_speed (unsigned char speed);
;
;/* Set the speed of the Chameleon cartridge, the following inputs
; * are accepted:
; * SPEED_SLOW : 1 Mhz mode
; * SPEED_1X : 1 Mhz mode
; * SPEED_2X : 2 Mhz mode
; * SPEED_3X : 3 Mhz mode
; * SPEED_4X : 4 Mhz mode
; * SPEED_5X : 5 Mhz mode
; * SPEED_6X : 6 Mhz mode
; * SPEED_FAST : Maximum speed mode
; *
; * Note that any value higher or equal to SPEED_7X will switch to maximum
; * speed mode.
; *
; * This function will return the actual speed the CPU is at after trying
; * to set the requested speed, to my knowledge the switching should not fail.
; *
; * This function does not check for the presence of the Chameleon cartridge,
; * make sure you use 'detect_chameleon();' before using.
; */
; unsigned char get_chameleon_speed (void);
;
;/* Get the speed of the Chameleon cartridge.
; *
; * Possible return values:
; * SPEED_SLOW : Slow mode
; * SPEED_2X : 2Mhz mode
; * SPEED_3X : 3Mhz mode
; * SPEED_4X : 4Mhz mode
; * SPEED_5X : 5Mhz mode
; * SPEED_6X : 6Mhz mode
; * SPEED_FAST : Maximum speed mode
; *
; * This function does not check for the presence of the Chameleon cartridge,
; * make sure you use 'detect_chameleon();' before using.
; */
.export _set_chameleon_speed
.export _get_chameleon_speed
.include "accelerator.inc"
_set_chameleon_speed:
cmp #SPEED_7X
bcs maximum_speed
cmp #SPEED_1X
beq low_speed
ora #$80
set_speed:
jsr activate_regs
sta CHAMELEON_CFGTUR
jmp return_speed
low_speed:
lda #CHAMELEON_CFGTUR_LIMIT_1MHZ
bne set_speed
maximum_speed:
lda #CHAMELEON_CFGTUR_LIMIT_NONE
bne set_speed
_get_chameleon_speed:
jsr activate_regs
return_speed:
ldx #$00
lda CHAMELEON_CFGTUR
tay
and #%10000000
beq return_value
tya
and #%00001000
bne is_slow_mode
tya
and #%00000111
beq is_max_mode
return_value:
ldy #CHAMELEON_DISABLE_REGS
sty CHAMELEON_CFGENA
rts
is_slow_mode:
txa
bne return_value
is_max_mode:
lda #SPEED_FAST
bne return_value
activate_regs:
ldy #CHAMELEON_ENABLE_REGS
sty CHAMELEON_CFGENA
rts