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added 4510 cpu detection to getcpu.s

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This commit is contained in:
Sven Oliver Moll 2016-09-07 19:44:11 +02:00
parent 7a9a7c3188
commit c0d2643952
2 changed files with 12 additions and 2 deletions
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1
include/6502.h
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@ -50,6 +50,7 @@ typedef unsigned size_t;
#define CPU_6502 0
#define CPU_65C02 1
#define CPU_65816 2
#define CPU_4510 3
unsigned char getcpu (void);
/* Detect the CPU the program is running on */

13
libsrc/common/getcpu.s
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@ -12,6 +12,7 @@
; - carry clear and 0 in A for a NMOS 6502 CPU
; - carry set and 1 in A for some CMOS 6502 CPU
; - carry set and 2 in A for a 65816
; - carry set and 3 in A for a 4510
;
; 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
@ -22,16 +23,24 @@
_getcpu:
lda #0
inc a ; .byte $1A
inc a ; .byte $1A ; nop on nmos, inc on every cmos
cmp #1
bcc @L9
; This is at least a 65C02, check for a 65816
; This is at least a 65C02, check for a 4510
.byte $42,$ea ; neg on 4510, nop #$ea on 65c02, wdm $ea on 65816
cmp #1
bne @L8
; check for 65816; after 4510, because $eb there is row (rotate word)
xba ; .byte $eb, put $01 in B accu
dec a ; .byte $3a, A=$00 if 65C02
xba ; .byte $eb, get $01 back if 65816
inc a ; .byte $1a, make $01/$02
.byte $2c ; bit instruction to skip next command
@L8: lda #3 ; CPU_4510 constant
@L9: ldx #0 ; Load high byte of word
rts