mirror of https://github.com/cc65/cc65.git
101 lines
2.5 KiB
ArmAsm
101 lines
2.5 KiB
ArmAsm
;
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; Marco van den Heuvel, 2018-04-25
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;
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; unsigned char __fastcall__ set_chameleon_speed (unsigned char speed);
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;
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;/* Set the speed of the Chameleon cartridge, the following inputs
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; * are accepted:
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; * SPEED_SLOW : 1 Mhz mode
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; * SPEED_1X : 1 Mhz mode
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; * SPEED_2X : 2 Mhz mode
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; * SPEED_3X : 3 Mhz mode
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; * SPEED_4X : 4 Mhz mode
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; * SPEED_5X : 5 Mhz mode
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; * SPEED_6X : 6 Mhz mode
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; * SPEED_FAST : Maximum speed mode
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; *
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; * Note that any value higher or equal to SPEED_7X will switch to maximum
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; * speed mode.
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; *
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; * This function will return the actual speed the CPU is at after trying
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; * to set the requested speed, to my knowledge the switching should not fail.
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; *
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; * This function does not check for the presence of the Chameleon cartridge,
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; * make sure you use 'detect_chameleon();' before using.
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; */
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; unsigned char get_chameleon_speed (void);
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;
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;/* Get the speed of the Chameleon cartridge.
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; *
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; * Possible return values:
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; * SPEED_SLOW : Slow mode
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; * SPEED_2X : 2Mhz mode
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; * SPEED_3X : 3Mhz mode
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; * SPEED_4X : 4Mhz mode
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; * SPEED_5X : 5Mhz mode
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; * SPEED_6X : 6Mhz mode
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; * SPEED_FAST : Maximum speed mode
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; *
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; * This function does not check for the presence of the Chameleon cartridge,
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; * make sure you use 'detect_chameleon();' before using.
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; */
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.export _set_chameleon_speed
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.export _get_chameleon_speed
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.include "accelerator.inc"
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_set_chameleon_speed:
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cmp #SPEED_7X
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bcs maximum_speed
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cmp #SPEED_1X
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beq low_speed
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ora #$80
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set_speed:
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jsr activate_regs
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sta CHAMELEON_CFGTUR
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jmp return_speed
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low_speed:
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lda #CHAMELEON_CFGTUR_LIMIT_1MHZ
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bne set_speed
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maximum_speed:
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lda #CHAMELEON_CFGTUR_LIMIT_NONE
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bne set_speed
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_get_chameleon_speed:
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jsr activate_regs
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return_speed:
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ldx #$00
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lda CHAMELEON_CFGTUR
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tay
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and #%10000000
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beq return_value
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tya
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and #%00001000
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bne is_slow_mode
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tya
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and #%00000111
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beq is_max_mode
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return_value:
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ldy #CHAMELEON_DISABLE_REGS
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sty CHAMELEON_CFGENA
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rts
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is_slow_mode:
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txa
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bne return_value
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is_max_mode:
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lda #SPEED_FAST
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bne return_value
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activate_regs:
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ldy #CHAMELEON_ENABLE_REGS
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sty CHAMELEON_CFGENA
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rts
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