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;; Parting out the big math/logic routines from the
;; instruction dispatch table.
alu_add:
;; ADD instruction
;; ADD d1,d0
;; d1 + d0 -> d1
move.b d0,f_tmp_src_b ; preserve operands for flag work
move.b d1,f_tmp_dst_b
move.b #1,(f_tmp_byte-flag_storage)(a3)
add d0,d1
move sr,(f_host_sr-flag_storage)(a3)
move.w #0202,(flag_byte-flag_storage)(a3)
rts
alu_adc:
;; ADC instruction
;; ADC d1,d0
;; d1 + d0 + carry -> d1
bsr flags_normalize
move.b flag_byte(pc),d2
andi.b #1,d2
add.b d0,d2
move.b d2,(f_tmp_src_b-flag_storage)(a3)
move.b d1,(f_tmp_dst_b-flag_storage)(a3)
add.b d2,d1
move sr,(f_host_ccr-flag_storage)(a3)
move.w #$0202,(flag_byte-flag_storage)(a3)
rts
alu_sbc:
;; SBC instruction
;; SBC d1,d0
;; d1 - (d0+C) -> d1
;; sets flags
push.l d2
bsr flags_normalize
move.b flag_byte(pc),d2
andi.b #1,d2
add.b d0,d2
move.b d2,(f_tmp_src_b-flag_storage)(a3)
move.b d1,(f_tmp_dst_b-flag_storage)(a3)
sub.b d2,d1
move sr,(f_host_sr-flag_storage)(a3)
move.w #$0202,(flag_byte-flag_storage)(a3)
pop.l d2
rts
alu_sub:
;; SUB instruction
;; SUB d1,d0
;; d1 - d0 -> d1
;; sets flags
;; XXX use lea and then d(an) if you have a spare register.
;; preserve operands for flagging
move.b d0,(f_tmp_src_b-flag_storage)(a3)
move.b d1,(f_tmp_dst_b-flag_storage)(a3)
move.b #1,(f_tmp_byte-flag_storage)(a3)
andi.b #%00000010,(flag_valid-flag_storage)(a3)
move.b #%00000010,(flag_byte-flag_storage)(a3)
sub d0,d1
move sr,(f_host_sr-flag_storage)(a3)
rts
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