mirror of https://github.com/cc65/cc65.git
60 lines
1.6 KiB
ArmAsm
60 lines
1.6 KiB
ArmAsm
;
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; Marco van den Heuvel, 2018-04-09
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;
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; unsigned char __fastcall__ set_scpu_speed (unsigned char speed);
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;
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;/* Set the speed of the SuperCPU cartridge, using SPEED_SLOW will switch to
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; * 1 Mhz mode, SPEED_20X or SPEED_FAST will switch to 20 Mhz mode.
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; *
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; * Note that any value lower than SPEED_20X will switch to 1 Mhz mode, and
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; * any value higher or equal to SPEED_20X will switch to 20 Mhz 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, if this is not the speed that was requested
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; * then possibly the hardware speed switch prevented any software speed
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; * switching.
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; *
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; * This function does not check for the presence of the SuperCPU cartridge,
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; * make sure you use 'detect_scpu();' before using.
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; */
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; unsigned char get_scpu_speed (void);
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;
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;/* Get the speed of the SuperCPU cartridge.
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; *
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; * Possible return values:
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; * SPEED_1X : 1 Mhz mode
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; * SPEED_20X : 20 Mhz mode
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; *
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; * This function does not check for the presence of the SuperCPU cartridge,
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; * make sure you use 'detect_scpu();' before using.
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; */
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.export _set_scpu_speed
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.export _get_scpu_speed
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.include "accelerator.inc"
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_set_scpu_speed:
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cmp #SPEED_20X
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bcs high_speed
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low_speed:
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sta SuperCPU_Slow
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jmp _get_scpu_speed
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high_speed:
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sta SuperCPU_Fast
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_get_scpu_speed:
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ldx #$00
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lda SuperCPU_Speed_Mode
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asl
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asl
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bcc is_fast_speed
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lda #SPEED_1X
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rts
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is_fast_speed:
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lda #SPEED_20X
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rts
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