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|
;; N =S
;; Z = Z
;; V ~ P
;; C= C
;;
;; =CCR= == z80==
;; XNZVC SZ5H3PNC
;; 00000 00000000
;; 00001 00000001
;; 00010 00000100
;; 00011 00000101
;; 00100 01000000
;; 00101 01000001
;; 00110 01000100
;; 00111 01000101
;; 01000 10000000
;; 01001 10000001
;; 01010 10000100
;; 01011 10000101
;; 01100 11000000
;; 01101 11000001
;; 01110 11000100
;; 01111 11000101
;; 10000 00000000
;; 10001 00000001
;; 10010 00000100
;; 10011 00000101
;; 10100 01000000
;; 10101 01000001
;; 10110 01000100
;; 10111 01000101
;; 11000 10000000
;; 11001 10000001
;; 11010 10000100
;; 11011 10000101
;; 11100 11000000
;; 11101 11000001
;; 11110 11000100
;; 11111 11000101
flags_set:
;; Routine to set the given flags
;; Noted in d0 by a 1 bit
or.b d0,flag_byte
or.b d0,flag_valid
rts
flags_clear:
;; Clear the given flags
;; Noted in d0 by a 1 bit
or.b d0,flag_valid
not.b d0
and.b d0,flag_byte
rts
;; Routine to turn 68k flags into z80 flags.
;; Preconditions:
;; Flags to change are noted in d0 by a 1 bit
flags_normalize:
move.b host_ccr,d1
movea lut_ccr(pc),a1
move.b (lut_ccr,a1),d1
;; XXX do this
rts
;; LUT for the CCR -> F mapping
lut_ccr:
dc.b %00000000
dc.b %00000001
dc.b %00000100
dc.b %00000101
dc.b %01000000
dc.b %01000001
dc.b %01000100
dc.b %01000101
dc.b %10000000
dc.b %10000001
dc.b %10000100
dc.b %10000101
dc.b %11000000
dc.b %11000001
dc.b %11000100
dc.b %11000101
dc.b %00000000
dc.b %00000001
dc.b %00000100
dc.b %00000101
dc.b %01000000
dc.b %01000001
dc.b %01000100
dc.b %01000101
dc.b %10000000
dc.b %10000001
dc.b %10000100
dc.b %10000101
dc.b %11000000
dc.b %11000001
dc.b %11000100
dc.b %11000101
lut_valid:
dc.b %11000101
storage:
;; 1 if tmp_???b is valid, 0 if tmp_???w is valid
f_tmp_byte: ds.b 0
;; 2 if P is 0, 3 if P is 1, 4 if P is Parity, 5 if P is oVerflow
f_tmp_p_type: ds.b 0
;; byte operands
f_tmp_src_b: ds.b 0
f_tmp_dst_b: ds.b 0
f_tmp_result_b: ds.b 0
EVEN ;; word operands
f_tmp_src_w: ds.w 0
f_tmp_dst_w: ds.w 0
f_tmp_result_w: ds.w 0
;; 000XNZVC
f_host_ccr: ds.b 0
EVEN
flag_byte: ds.b 0 ; Byte of all flags
flag_valid: ds.b 0 ; Validity mask -- 1 if valid.
|
