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add support for detecting 45GS02

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Paul Gardner-Stephen 2018-12-27 10:50:25 +10:30 committed by greg-king5
parent 80a43d732d
commit 19ca1f6b48
2 changed files with 84 additions and 16 deletions
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1
include/6502.h
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@ -55,6 +55,7 @@ typedef unsigned size_t;
#define CPU_65CE02 5
#define CPU_HUC6280 6
#define CPU_2A0x 7
#define CPU_45GS02 8
unsigned char getcpu (void);
/* Detect the CPU the program is running on */

99
libsrc/common/getcpu.s
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@ -17,6 +17,7 @@
; - carry set and 5 in A for a 65CE02
; - carry set and 6 in A for a HuC6280
; - carry clear and 7 in A for a 2a03/2a07
; - carry set and 8 in A for a 45GS02
;
; This function uses a $1A opcode which is a INA on the 816 and ignored
; (interpreted as a NOP) on a NMOS 6502. There are several CMOS versions
@ -26,52 +27,119 @@
.p816 ; Enable 65816 instructions
_getcpu:
lda #0
inc a ; .byte $1A ; nop on nmos, inc on every cmos
cmp #1
bcc @L8
bcc @IsNMOS
; This is at least a 65C02, check for a 65CE02/4510
.byte $42,$EA ; neg on 65CE02/4510, nop #$EA on 65C02, wdm $EA on 65816
cmp #1
beq @L6
beq @HasINCA
; This is at least a 65CE02, check for 4510
lda #5 ; CPU_65CE02 constant
ldx #0 ; to make sure MAP doesn't do anything, the upper nybl of X and Z must be clear
.byte $5C ; map on 4510, aug on 65CE02 (acts like 4 byte nop)
lda #3 ; CPU_4510 constant
nop
bne @L9
cmp #5
beq @LoadXAndReturn
; It is either a 4510 (C65) or a 45GS02 (MEGA65)
; 45GS02 supports 32-bit ZP indirect, so use that to check CPU type
; without requiring a functioning MEGA65 hypervisor.
; We setup a read of $200FF, then store a different value in $00FF
; and then re-read $200FF to see if it is unchanged.
; Save the 32-bit ZP pointer and data byte
ldx #4
@L10: lda $fb,x
sta @GetCPUTemp,x
dex
bpl @L10
; Setup 32-bit pointer to $000200FF
lda #$ff
sta $fb
lda #$00
sta $fc
sta $fe
lda #$02
sta $fd
; Prefixing LDA ($nn),Z with a NOP uses 32-bit ZP pointer on 45GS02,
; but normal 16-bit ZP pointer on 4510
; (We assume Z=$00, which will be the normal case)
nop ; prefix to tell next instruction to be 32-bit ZP
.byte $b2,$fb ; LDA ($nn),Z
eor #$ff ; change the value
sta $ff ; store in $FF
; now try again to load it: If the same, then 45GS02, as $200FF is unchanged
nop ; prefix to tell next instruction to be 32-bit ZP
.byte $b2,$fb ; LDA ($nn),Z
cmp $ff ; does the loaded value match what is in $FF?
beq @Is4510 ; matches, so must be a 4510 = C65
bne @Is45GS02 ; $200FF and $FF have different values, so must be a MEGA65 45GS02
@Is4510:
jsr @RestoreGetCPUTemp
lda #3 ; CPU_4510 constant
ldx #0 ; load high byte of word
rts
@Is45GS02:
jsr @RestoreGetCPUTemp
lda #8 ; CPU_45GS02 constant
ldx #0 ; load high byte of word
rts
@RestoreGetCPUTemp:
; Save the 32-bit ZP pointer and data byte
ldx #4
@L11: lda @GetCPUTemp,x
sta $fb,x
dex
bpl @L11
rts
; Temporary storage for the ZP locations we modify above
@GetCPUTemp: .byte 0,0,0,0,0
; 6502 type of cpu, check for a 2a03/2a07
@L8:
@IsNMOS:
sed ; set decimal mode, no decimal mode on the 2a03/2a07
lda #9
clc
adc #1 ; $01+$09 = $10 on 6502, $01+$09 = $0A on 2a03/2a07
cld
cmp #$0a
beq @L5
beq @Is2a03
lda #0 ; CPU_6502 constant
beq @L9
@L5:
beq @LoadXAndReturn
@Is2a03:
lda #7 ; CPU_2A0x constant
bne @L9
bne @LoadXAndReturn
; 65C02 cpu type, check for HuC6280
@L4: ldx #6 ; CPU_HUC6280 constant
@CheckHuC6280:
ldx #6 ; CPU_HUC6280 constant
.byte $22,$EA ; sax nop on HuC6280 (A=$06, X=$01), nop #$EA on 65C02 (A=$01, X=$06)
bne @L9
bne @LoadXAndReturn
; Check for 65816/65802
@L6: xba ; .byte $EB, put $01 in B accu (nop on 65C02/65SC02)
@HasINCA:
xba ; .byte $EB, put $01 in B accu (nop on 65C02/65SC02)
dec a ; .byte $3A, A=$00
xba ; .byte $EB, A=$01 if 65816/65802 and A=$00 if 65C02/65SC02
inc a ; .byte $1A, A=$02 if 65816/65802 and A=$01 if 65C02/65SC02
cmp #2
beq @L9
beq @LoadXAndReturn
; check for 65SC02
@ -82,9 +150,8 @@ _getcpu:
ldx $F7
sty $F7
cpx #$00
bne @L4
bne @CheckHuC6280
lda #4 ; CPU_65SC02 constant
@L9: ldx #0 ; Load high byte of word
@LoadXAndReturn:
ldx #0
rts