diff options
Diffstat (limited to 'flags.asm')
| -rw-r--r-- | flags.asm | 309 |
1 files changed, 0 insertions, 309 deletions
diff --git a/flags.asm b/flags.asm deleted file mode 100644 index 6282336..0000000 --- a/flags.asm +++ /dev/null @@ -1,309 +0,0 @@ - ;; Routine to set the given flags - ;; Noted in \1 by a 1 bit -F_SET MACRO ; 32 cycles, 8 bytes - or.b \1,flag_byte-flag_storage(a3) - or.b \1,flag_valid-flag_storage(a3) - ENDM - - ;; Clear the given flags - ;; Noted in \1 (must be a reg) by a 1 bit -F_CLEAR MACRO ; 36 cycles, 10 bytes - or.b \1,flag_valid-flag_storage(a3) - not.b \1 - and.b \1,flag_byte-flag_storage(a3) - ENDM - - ;; Use this when an instruction uses the P/V bit as Parity. - ;; Sets or clears the bit explicitly. - ;; - ;; Byte for which parity is calculated must be in \1. High - ;; byte of \1.w must be zero, using d0 is suggested. (a0,d1 - ;; destroyed) - -F_PAR MACRO - ori.b #%00000100,flag_valid-flag_storage(a3) - move.b flag_byte(pc),d1 - andi.b #%11111011,d1 - lea lut_parity(pc),a0 - or.b 0(a0,\1.w),d1 - move.b d1,flag_byte-flag_storage(a3) - ENDM - - - ;; Use this when an instruction uses the P/V bit as Overflow. - ;; Leaves the bit itself implicit; simply marks it dirty. -F_OVFL MACRO ; 20 cycles, 6 bytes - andi.b #%11111011,flag_valid-flag_storage(a3) - ENDM - - ;; Save the two operands from ADD \1,\2 -F_ADD_SAVE MACRO - move.b \1,f_tmp_src_b-flag_storage(a3) - move.b \2,f_tmp_dst_b-flag_storage(a3) - move.b #$01,f_tmp_byte-flag_storage(a3) - F_SET #% - ENDM - - ;; Normalize and return inverse of emulated Carry bit (loaded - ;; into host zero flag) - - ;; Destroys d1 -f_norm_c: - move.b flag_valid-flag_storage(a3),d1 -; d1 is destroyed in all cases, so you can use lsr and the C bit (same speed, smaller) - lsr.b #1,d1 - bcs.s FNC_ok ; Bit is valid - move.b (f_host_sr+1)-flag_storage(a3),d1 - andi.b #%00000001,d1 - or.b d1,flag_byte-flag_storage(a3) - ori.b #%00000001,flag_valid-flag_storage(a3) -FNC_ok: - move.b flag_byte-flag_storage(a3),d1 - andi.b #%00000001,d1 - rts - - ;; Normalize and return **INVERSE** of emulated Zero bit - ;; (loaded into host's zero flag) - - ;; Destroys d1 -f_norm_z: - move.b flag_valid-flag_storage(a3),d1 - andi.b #%01000000,d1 - bne.s FNZ_ok ; Bit is valid - bsr flags_normalize -FNZ_ok: - move.b flag_byte-flag_storage(a3),d1 - andi.b #%01000000,d1 - rts - - ;; Normalize and return **INVERSE** of emulated Parity/oVerflow - ;; bit (loaded into host zero flag) - - ;; Destroys d1 -f_norm_pv: - move.b flag_valid-flag_storage(a3),d1 - andi.b #%00000100,d1 - bne.s FNPV_ok ; Bit is already valid - bsr flags_normalize -FNPV_ok: - move.b flag_byte-flag_storage(a3),d1 - andi.b #%00000100,d1 - rts - - ;; Calculate the P/V bit as Parity, for the byte in - ;; d1. Destroys d0,d1. -f_calc_parity: - andi.w #$ff,d1 - move.b lut_parity-flag_storage(a3,d1.w),d1 - move.b (flag_byte),d0 - and.b #%11110111,d0 - or.w #%0000100000000000,d0 - or.b d1,d0 - move.w d0,flag_byte-flag_storage(a3) - 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 == 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 == 3 { - ;; // it's a byte - ;; add f_tmp_src_b to f_tmp_dst_b - ;; create a carry and output - ;; add low nybbles only - ;; 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 inverse of emulated Sign bit (loaded - ;; into host zero flag). - - ;; Destroys d1 -f_norm_sign: - move.b flag_valid-flag_storage(a3),d1 - andi.b #%01000000,d1 - bne.s FNsign_ok ; Bit is already valid - bsr flags_normalize -FNsign_ok: - move.b flag_byte-flag_storage(a3),d1 - andi.b #%01000000,d1 - rts - - ;; Routine to turn 68k flags into z80 flags. -flags_normalize: - move.b (f_host_sr+1)(pc),d1 ; 8/4 - ;; .w keeps d1 clean - andi.w #%00011111,d1 ; 8/4 - - ;; doesn't this invalidate the previous contents of d1 - ;; entirely? - move.b lut_ccr(pc,d1.w),d1 ; 10/4 - move.b flag_valid(pc),d0 - not.b d0 - and.b d0,d1 ; Mask out all the unwanted bits - not.b d0 - ori.b #%11000101,d0 ; These are the z80 flag register bits that can be derived from the 68k CCR. - move.b d0,flag_valid-flag_storage(a3) - or.b d1,flag_byte-flag_storage(a3) - rts - - ;; Routine to completely fill the flags register -flags_all: - bsr flags_normalize - bsr f_calc_carries - rts - - EVEN -flag_storage: - ;; 0 if the flag is already 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 uncalculated Parity - ;; 5 if P is uncalculated oVerflow -f_tmp_p_type: dc.b 0 - - ;; byte operands -f_tmp_src_b: dc.b 0 -f_tmp_dst_b: dc.b 0 -f_tmp_result_b: dc.b 0 - - EVEN -f_tmp_src_w: dc.w 0 -f_tmp_dst_w: dc.w 0 -f_tmp_result_w: dc.w 0 - - ;; 000XNZVC - EVEN - ;; DO NOT REARRANGE THESE -f_host_sr: dc.w 0 -f_host_ccr: dc.b 0 ;XXX make overlap somehow? - - EVEN - ;; DO NOT REARRANGE THESE. -flag_byte: dc.b 0 ; Byte of all flags -flag_valid: dc.b 0 ; Validity mask -- 1 if valid. - - - ;; LUT for the CCR -> F mapping -lut_ccr: - ;; N =S - ;; Z = Z - ;; V ~ P - ;; C= C - ;; - ;; =CCR= == z80== - ;; XNZVC SZ5H3PNC - dc.b %00000000 ;; 00000 00000000 - dc.b %00000001 ;; 00001 00000001 - dc.b %00000100 ;; 00010 00000100 - dc.b %00000101 ;; 00011 00000101 - dc.b %01000000 ;; 00100 01000000 - dc.b %01000001 ;; 00101 01000001 - dc.b %01000100 ;; 00110 01000100 - dc.b %01000101 ;; 00111 01000101 - dc.b %10000000 ;; 01000 10000000 - dc.b %10000001 ;; 01001 10000001 - dc.b %10000100 ;; 01010 10000100 - dc.b %10000101 ;; 01011 10000101 - dc.b %11000000 ;; 01100 11000000 - dc.b %11000001 ;; 01101 11000001 - dc.b %11000100 ;; 01110 11000100 - dc.b %11000101 ;; 01111 11000101 - dc.b %00000000 ;; 10000 00000000 - dc.b %00000001 ;; 10001 00000001 - dc.b %00000100 ;; 10010 00000100 - dc.b %00000101 ;; 10011 00000101 - dc.b %01000000 ;; 10100 01000000 - dc.b %01000001 ;; 10101 01000001 - dc.b %01000100 ;; 10110 01000100 - dc.b %01000101 ;; 10111 01000101 - dc.b %10000000 ;; 11000 10000000 - dc.b %10000001 ;; 11001 10000001 - dc.b %10000100 ;; 11010 10000100 - dc.b %10000101 ;; 11011 10000101 - dc.b %11000000 ;; 11100 11000000 - dc.b %11000001 ;; 11101 11000001 - dc.b %11000100 ;; 11110 11000100 - dc.b %11000101 ;; 11111 11000101 - - ;; 256-byte LUT for the Parity bit. - ;; Keep this last so all storage references require only one - ;; extension word. - ;; - ;; This table taken from another z80 emulator -lut_parity: - dc.b 4,0,0,4,0,4,4,0,0,4,4,0,4,0,0,4 - dc.b 0,4,4,0,4,0,0,4,4,0,0,4,0,4,4,0 - dc.b 0,4,4,0,4,0,0,4,4,0,0,4,0,4,4,0 - dc.b 4,0,0,4,0,4,4,0,0,4,4,0,4,0,0,4 - dc.b 0,4,4,0,4,0,0,4,4,0,0,4,0,4,4,0 - dc.b 4,0,0,4,0,4,4,0,0,4,4,0,4,0,0,4 - dc.b 4,0,0,4,0,4,4,0,0,4,4,0,4,0,0,4 - dc.b 0,4,4,0,4,0,0,4,4,0,0,4,0,4,4,0 - dc.b 0,4,4,0,4,0,0,4,4,0,0,4,0,4,4,0 - dc.b 4,0,0,4,0,4,4,0,0,4,4,0,4,0,0,4 - dc.b 4,0,0,4,0,4,4,0,0,4,4,0,4,0,0,4 - dc.b 0,4,4,0,4,0,0,4,4,0,0,4,0,4,4,0 - dc.b 4,0,0,4,0,4,4,0,0,4,4,0,4,0,0,4 - dc.b 0,4,4,0,4,0,0,4,4,0,0,4,0,4,4,0 - dc.b 0,4,4,0,4,0,0,4,4,0,0,4,0,4,4,0 - dc.b 4,0,0,4,0,4,4,0,0,4,4,0,4,0,0,4 - - ;; To save space I might be able to overlay the Parity table - ;; with the CCR table, or even interleave it in the opcodes. - - |