diff options
Diffstat (limited to 'alu.s')
| -rw-r--r-- | alu.s | 95 |
1 files changed, 95 insertions, 0 deletions
@@ -0,0 +1,95 @@ + ;; Parting out the big math/logic routines from the + ;; instruction dispatch table. + +.text + +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 + add d0,d1 + move sr,f_host_sr + move.w #0202,flag_byte + 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 + move.b d1,f_tmp_dst_b + add.b d2,d1 + move sr,f_host_ccr + move.w #$0202,flag_byte + 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 + move.b d1,f_tmp_dst_b + sub.b d2,d1 + move sr,f_host_sr + move.b #$02,flag_byte + move.b #$02,flag_valid + 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 + move.b d1,f_tmp_dst_b + move.b #1,f_tmp_byte + andi.b #%00000010,flag_valid + move.b #%00000010,flag_byte + sub d0,d1 + move sr,f_host_sr + rts + +alu_and: + ;; XXX do this + rts + +alu_xor: + ;; XXX do this + rts + +alu_or: + ;; XXX do this + rts + +alu_cp: + ;; Same as SUB but the macro that calls this doesn't save the + ;; result. + + ;; SPEED can hardcode one of the arguments to always be the A register. + move.b d0,f_tmp_src_b + move.b d1,f_tmp_dst_b + move.b #1,f_tmp_byte + andi.b #%00000010,flag_valid + move.b #%00000010,flag_byte + sub.b d0,d1 + move sr,f_host_sr + rts |