Added C64 Turbo Master accelerator code and documentation.

libsrc/c64/acc_detect_turbomaster.s

@@ -0,0 +1,47 @@
+;
+; Marco van den Heuvel, 2018-04-30
+;
+
+; unsigned char detect_turbomaster (void);
+;
+;/* Check for the presence of a Turbo Master cartridge.
+; *
+; * Possible return values:
+; * 0x00  : TurboMaster cartridge not present
+; * 0x01  : TurboMaster cartridge present
+; */
+
+        .export         _detect_turbomaster
+
+        .include        "accelerator.inc"
+
+_detect_turbomaster:
+        lda     #$00
+        tax
+
+; Make sure the current CPU is not a 6510
+        .byte   $1A                   ; NOP on 8502, INA on 65(S)C(E)02, 4510 and 65816
+        beq     not_found
+
+; Make sure the current CPU is not a 65816
+        clc
+        .byte   $E2,$01                ; NOP #$01 on 65(S)C02, LDA $(01,S),Y on 65CE02 and 4510, SEP #$01 on 65816
+        bcs     not_found              ; carry will be set on 65816
+
+; Make sure the current CPU is not a 65CE02/4510
+        .byte   $A3,$A3                ; NOP NOP on 65(S)C02 and LDZ #$00 on 65CE02 and 4510
+        .byte   $6B                    ; NOP on 65(S)C02 and TZA on 65CE02 and 4510
+        cmp     #$A3
+        beq     not_found
+
+; Check for turbo master basic replacement
+        ldy     TURBOMASTER_DETECT
+        cpy     #$A2
+        bne     not_found
+found:
+        lda     #$01
+        .byte   $24
+not_found:
+        txa
+        rts
+