diff options
| -rw-r--r-- | flags.asm | 50 |
1 files changed, 46 insertions, 4 deletions
@@ -98,17 +98,18 @@ f_calc_parity: rts ;; Routine to make both the Carry and Half-Carry flags valid. + ;; Trashes d0, d1. f_calc_carries: ;; XXX do this ;; if f_tmp_byte == 0 { ;; return, shit is valid - ;; } else if f_tmp_byte == 1 { + ;; } else if f_tmp_byte == 2 { ;; // it's a word ;; add f_tmp_src_w to f_tmp_dst_w ;; low bytes only, create a carry and save ;; then high bytes, create a carry and output ;; then 3rd nibble, create a half-carry and output - ;; } else if f_tmp_byte == 2 { + ;; } else if f_tmp_byte == 3 { ;; // it's a byte ;; add f_tmp_src_b to f_tmp_dst_b ;; create a carry and output @@ -116,6 +117,47 @@ f_calc_carries: ;; create a half-carry and output ;; } ;; set f_tmp_byte = 0 + pushm d2-d5 ; how many registers do I need? + move.b f_tmp_byte(pc),d0 + bne f_cc_dirty + rts +f_cc_dirty: + cmpi.b #2,d0 + bne f_cc_byte + ;; it's a word! + move.w f_tmp_src_w(pc),d2 + move.w f_tmp_dst_w(pc),d3 + move.w d3,d4 + add.w d2,d3 + move sr,d5 + andi.w #1,d5 + rol #8,d5 + andi.w #$0fff,d2 + andi.w #$0fff,d4 + add.w d2,d4 + andi.l #$1000,d4 + ori.w #%00010001,d5 + or.w d4,d5 + or.w d5,flag_byte-flag_storage(a3) + clr.b f_tmp_byte-flag_storage(a3) + popm d2-d5 + rts +f_cc_byte: + move.b f_tmp_src_b(pc),d2 + move.b f_tmp_dst_b(pc),d3 + move.b d3,d4 + add.b d2,d3 + move sr,d5 + andi.b #1,d5 + andi.b #$0f,d2 + andi.b #$0f,d4 + add.b d2,d4 + andi.b #$10,d4 + or.b d4,d5 + or.b d5,flag_byte-flag_storage(a3) + clr.b f_tmp_byte-flag_storage(a3) + or.b #%00010001,flag_valid-flag_storage(a3) + popm d2-d5 rts ;; Normalize and return Sign bit (loaded into Z bit). @@ -153,8 +195,8 @@ flags_all: flag_storage: ;; 0 if the flag is already valid - ;; 1 if tmp_???b is valid - ;; 2 if tmp_???w is valid + ;; 2 if tmp_???b is valid + ;; 3 if tmp_???w is valid f_tmp_byte: dc.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: dc.b 0 |