started work on setting text mode

src/kernal/extapi_m65/mega65__jumptable.s

@@ -0,0 +1,27 @@
+// #LAYOUT# M65 KERNAL_0 #TAKE
+// #LAYOUT# *   *        #IGNORE
+
+//
+// Not this is not an official Kernal API extension (yet)! It is subject to change!
+//
+// XXX consider turning this into vector table, the only jumptable extension
+// would copy the vector table to given memory location
+
+
+M65_JMODE64:
+	jsr M65_MODE64
+
+M65_JMODE65:
+	jsr M65_MODE65
+
+M65_JISMODE65:
+	jsr M65_ISMODE65
+
+M65_JSLOW:
+	jsr M65_SLOW
+
+M65_JFAST:
+	jsr M65_FAST
+
+M65_JSELDEV:
+	jsr SELDEV

src/kernal/extapi_m65/mega65_ismode64.s

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+// #LAYOUT# M65 KERNAL_0 #TAKE
+// #LAYOUT# *   *        #IGNORE
+
+
+M65_ISMODE65: // checks if mode is native M65 one, BEQ = jump if native mode
+
+	pha
+
+	lda M65_MAGICSTR+0
+	cmp #$4D // 'M'
+	bne !+
+	lda M65_MAGICSTR+1
+	cmp #$36 // '6'
+	bne !+
+	lda M65_MAGICSTR+2
+	cmp #$35 // '5'
+!:
+	pla
+	rts

src/kernal/extapi_m65/mega65_mode64.s

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+// #LAYOUT# M65 KERNAL_1 #TAKE
+// #LAYOUT# *   *        #IGNORE
+
+
+M65_MODE64:
+
+	// Disable interrupts, they might interfere
+
+	sei
+
+	// XXX provide full implementation
+
+	// Set the magic string to mark legacy mode
+
+	lda #$00
+	sta M65_MAGICSTR+0
+	sta M65_MAGICSTR+1
+	sta M65_MAGICSTR+2
+
+	// Reenable interrupts
+
+	cli
+
+	// Switch CPU speed back to slow and quit
+
+	jmp M65_SLOW

src/kernal/extapi_m65/mega65_mode65.s

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+// #LAYOUT# M65 KERNAL_1 #TAKE
+// #LAYOUT# *   *        #IGNORE
+
+
+M65_MODE65:
+
+	// Disable interrupts, they might interfere
+
+	sei
+
+	// Switch CPU speed to fast
+
+	jsr M65_FAST
+
+	// Set the magic string to mark native mode
+
+	lda #$4D // 'M'
+	sta M65_MAGICSTR+0
+	lda #$36 // '6'
+	sta M65_MAGICSTR+1
+	lda #$35 // '5'
+	sta M65_MAGICSTR+2
+
+	// Switch VIC to VIC-IV mode
+
+	jsr viciv_unhide
+
+	// Set screen mode to 80x25
+
+	lda #$01
+	jsr m65_scrmodeset_internal
+
+	// Clear the screen
+
+	jmp M65_CLRSCR

src/kernal/extapi_m65/mega65_slow_fast.s

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+// #LAYOUT# M65 KERNAL_0 #TAKE
+// #LAYOUT# *   *        #IGNORE
+
+
+M65_SLOW: // set CPU speed to 1 MHz
+
+	lda #$40
+	skip_2_bytes_trash_nvz
+
+	// FALLTROUGH
+
+M65_FAST: // set CPU speed to 40 MHz
+
+	lda #$41
+	sta CPU_D6510
+	rts