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/////////////////////////////////////////////////////////////////////////////////////////////////// // // // file name: inst_exec.v // // description: main execution engine for wishbone z80 // // project: wb_z80 // // // // Author: B.J. Porcella // // e-mail: bporcella@sbcglobal.net // // // // // // // /////////////////////////////////////////////////////////////////////////////////////////////////// // // // Copyright (C) 2000-2002 B.J. Porcella // // Real Time Solutions // // // // // // This source file may be used and distributed without // // restriction provided that this copyright statement is not // // removed from the file and that any derivative work contains // // the original copyright notice and the associated disclaimer. // // // // THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY // // EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED // // TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS // // FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL THE AUTHOR // // OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, // // INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES // // (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE // // GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR // // BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF // // LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT // // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT // // OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE // // POSSIBILITY OF SUCH DAMAGE. // // // //-------1---------2---------3--------Comments on file -------------7---------8---------9--------0 // // This file contains the data related registers of the z80 and the // logic required to update them. Included registers are: // ar fr // br cr // dr er // hr lr // ixr // iyr // intr // // and the "prime" registers // ap fp // bp cp // dp ep // hp lp // // This logic can be considered a "slave" to the memstate sequencer (in memstate2.v). // as memstate sequencer executes any instruction from ir1 (the of - os pipe) the instruction // gets transferred to ir2 - which now becomes active. // // In the case of any memory type instruction (HL) , the pipeline must stall 1 tick to get the // operand into the nn register. This file logic needs not understand any of that -- just // execute when told to (ir2_val). // // From a block diagram standpoint this file is somewhat messy. There are multiple ALU's and // multiple source multiplexors. Part of the reason for this is hardware speed - the // various additions start pretty early in the cycle ( as not much decode logic is needed to // get them started. In parallel with that - the destination selectors ( which require more // complex decoding logic ) are "doing thier thing" No claim that this is absolute optimum - any // good synthesizer should be able to make the basic structure faster when flattened. However, // the intention is that even if the synthesizer is pretty primitive -- reasonably fast hardware // will be produced. // //-------1---------2---------3--------CVS Log -----------------------7---------8---------9--------0 // // $Id: inst_exec.v,v 1.1 2004-04-17 07:39:21 mihal Exp $ // // $Date: 2004-04-17 07:39:21 $ // $Revision: 1.1 $ // $Author: mihal $ // $Locker: $ // $State: Exp $ // // Change History: // $Log: not supported by cvs2svn $ // Revision 1.1.1.1 2004/04/13 23:49:54 bporcella // import first files // // // //-------1---------2---------3--------Module Name and Port List------7---------8---------9--------0 module inst_exec( br_eq0, cr_eq0, upd_ar, upd_br, upd_cr, upd_dr, upd_er, upd_hr, upd_lr,upd_fr, ar, fr, br, cr, dr, er, hr, lr, intr, ixr, iyr, add16, exec_ir2, exec_decbc, exec_decb, ir2, clk, rst, nn, sp, dd_grp, fd_grp ); //-------1---------2---------3--------Output Ports---------6---------7---------8---------9--------0 output br_eq0; output cr_eq0; output upd_ar, upd_br, upd_cr, upd_dr, upd_er, upd_hr, upd_lr,upd_fr; output [7:0] ar, fr, br, cr, dr, er, hr, lr, intr; output [15:0] ixr, iyr; output [15:0] add16; //-------1---------2---------3--------Input Ports----------6---------7---------8---------9--------0 input exec_ir2; input exec_decbc; // in general this needs to happen at different time from exec input exec_decb; // in general - we don't have the EB instruction (yet) when this hits input [9:0] ir2; input clk; input rst; input [15:0] nn, sp; input dd_grp; // this must be ir2 input fd_grp; //-------1---------2---------3--------Parameters-----------6---------7---------8---------9--------0 `include "opcodes.v" //-------1---------2---------3--------Wires----------------6---------7---------8---------9--------0 wire [7:0] src_pqr; // arithmetic sources gven by ir2[2:0] wire [7:0] src_hr ; wire [7:0] src_lr ; wire [7:0] alu_out; // {CF. 8bit_result} wire alu_cry; wire c_in0, c_out7, c_in8, c_out11, cout15; wire [15:0] src_a, src_b; wire [15:0] add16; wire sf, zf, f5f, hf, f3f, pvf, nf, cf; wire [7:0] daa_alu; // {cry, number} hf goes to 0 always. wire daa_cry; wire upd_ar, upd_br, upd_cr, upd_dr, upd_er, upd_fr, upd_hr, upd_lr; wire c_8out3; wire [7:0] add_8bit; wire src_dblhr ; wire src_cb_r20 ; wire src_pqr20 ; wire src_pqr53 ; wire src_dbl ; wire [7:0] alu8_fr ; wire alu8_nf ; wire c_8out7 ; wire alu8_cry ; wire alu8_hcry ; wire [7:0] alu8_out ; wire add16_ofl ; wire c_16out7 ; wire c_16out11 ; wire c_16out15 ; wire c_16in0 ; wire sh_cry ; wire [7:0] sh_alu ; wire sh_alu_act ; wire bit_alu_act ; wire [7:0] bit_alu ; wire [7:0] decc_alu ; wire [7:0] decb_alu ; wire upd_a_alu8 ; wire up_a_sh_alu ; wire up_a_src_pqr ; wire up_a_n ; wire upd_b_alu8 ; wire up_b_src_pqr ; wire up_b_add16 ; wire [7:0] sh_src ; wire up_c_add16 ; wire upd_c_alu8 ; wire up_c_src_pqr ; wire up_d_add16 ; wire upd_d_alu8 ; wire up_d_src_pqr ; wire up_e_add16 ; wire upd_e_alu8 ; wire up_e_src_pqr ; wire up_h_add16 ; wire upd_h_alu8 ; wire upd_h_src_pqr ; wire up_l_add16 ; wire upd_l_alu8 ; wire upd_l_src_pqr ; wire upd_fr_alu8 ; wire upd_fr_add16 ; wire upd_fr_edadd16 ; wire upd_fr_sh ; wire upd_fr_cbsh ; wire eb_blk_mv ; //-------1---------2---------3--------Registers------------6---------7---------8---------9--------0 reg [7:0] ar, fr, br, cr, dr, er, hr, lr, intr; reg [7:0] ap, fp, bp, cp, dp, ep, hp, lp; reg [15:0] ixr, iyr; //-------1---------2---------3--------Assignments----------6---------7---------8---------9--------0 // it appears that dd and fd as a prefix to cb has a significantly modfied fuction...... // specifically, it is assumed that a memory operation is to be implemented (ix + d) // , In fact the // pipeline is such that we can make a fetch for free - so we will do that..... the // prefix flags should not be set here -- all we will know on execution is that it is a // cb instruction. ---- src is always nn assign src_hr = dd_grp ? ixr[15:8] : fd_grp ? iyr[15:8] : hr ; assign src_lr = dd_grp ? ixr[7:0] : fd_grp ? iyr[7:0] : lr ; assign src_dblhr = dd_grp ? ixr : // ed grp instructions (ADC HL ; SBC HL are not affected - fd_grp ? iyr : // instruction assembler assures this - ed_grp has no prefix {hr, lr} ; assign src_cb_r20 = (ddcb_grp | fdcb_grp) ? nn[7:0] : cb_grp ? src_pqr20 : ar ; assign src_pqr20 = {8{ir2[2:0]==REG8_B }} & br | {8{ir2[2:0]==REG8_C }} & cr | {8{ir2[2:0]==REG8_D }} & dr | {8{ir2[2:0]==REG8_E }} & er | {8{ir2[2:0]==REG8_H }} & src_hr | {8{ir2[2:0]==REG8_L }} & src_lr | {8{ir2[2:0]==REG8_MEM}} & nn[7:0] | {8{ir2[2:0]==REG8_A }} & ar ; assign src_pqr53 = {8{ir2[5:3]==REG8_B }} & br | {8{ir2[5:3]==REG8_C }} & cr | {8{ir2[5:3]==REG8_D }} & dr | {8{ir2[5:3]==REG8_E }} & er | {8{ir2[5:3]==REG8_H }} & src_hr | {8{ir2[5:3]==REG8_L }} & src_lr | {8{ir2[5:3]==REG8_MEM}} & nn[7:0] | {8{ir2[5:3]==REG8_A }} & ar ; assign src_dbl = {16{ir2[5:4]==2'b00}} & {br, cr} | {16{ir2[5:4]==2'b01}} & {dr, er} | {16{ir2[5:4]==2'b10}} & src_sshr | {16{ir2[5:4]==2'b11}} & sp ; // I wonder how well the synthesizer can reduce this??? - It is probably worth spending // some time during physical design to see if a more low level description would help -- // there is somebody out there who knows - and there is probably a good low level description. // // guess its kind of important to understand precisely what the synthesizer does // with some of the status things we need also. // // // The nastiest status to get is HF. Really need 4 bit adders to do that ( or reproduce a lot // of logic.) I don't have a lot of confdence in the synthesier's ability to minimize arithmetic // operations -- Its a moving target of course, but I've seen some really silly stuff come out // of synthesis when you use a "+" operator. guess I will be pretty explicit here. // Documentation of the HF is srange. IN and OUT operators are defined as X -- but 16 bit operations // get set by CRY from bit 11. (Do I care??? ) well probably not but it is documented - so should // be tested i guess. // // // may want to re-define as a module with carry look-ahead ? // // Had a notion to define a single adder - subtractor for both 8 and 16 bit operations, but // getting into source mux issues that solution scared me..... Worry the cry flag might // become a worst case path. As defined, a good chunk of the decode process can go on in // parallel with the cry computation --- with final decisions made using a small mux at // the flag register. // ------------ 8 bit adder for accumulator ops plus the INC DEC ops --------------------- // It is documented that the hf is modified by the INC and DEC ops even if ar is not the // destination of result --- clearly hf and nf are pretty usless on a INC B but ours is // not to reason why :-) ---- well its fun to bitch about silly stuff like this. // ( not as much fun to deal with instruction tests testing "features" -- or worse programmers // who figure out ways to use theses "features". ) // // 8 bit adder with cry out of bit 3 used for most operations on A as well as the // inc/dec instructions. also need to get ED44 (ar <= -ar) working here wire [7:0] src_pqri; // use just here and below wire [7:0] src_aor_cnst = ed_blk_cp ? ar : // CPI CPIR CPD CPDR ed_grp ? 8'h0 : // for ed44 -a ir2[7] ? ar : ir2[0] ? 8'hff : 8'h00 ; //--------------- the "standard" flag logic ----------------------------- // sf zf f5f hf assign alu8_fr ={alu8_out[7], ~|alu8_out, alu8_out[5], alu8_hcry, // f3f fpv fn fc alu8_out[3], alu8_out[7], alu8_nf, c_8out7 }; //assign alu8_pvf = (ir2[7:3]==5'b10100 | ir2[7:3]==5'b10101 | ir2[7:3]==5'b10110) ? // ~^alu8_out : // even parity // (src_aor_cnst[7]==src_pqri[7]) & (src_aor_cnst[7]!=alu8_out[7]) ; // ofl assign alu8_nf = (ir2[7:3]==5'b10010) | (ir2[7:3]==5'b10011) | (ir2[7:6]==2'b00) & ir2[0] | ed_grp ; assign {c_8out3, add_8bit[3:0]} = {1'b0, src_aor_cnst[3:0]} + {1'b0, src_pqri[3:0]} + {4'b0, c_8in0}; //wire [4:0] ha_temp = {1'b0, src_aor_cnst[3:0]} + {1'b0, src_pqri[3:0]} + {4'b0, c_8in0}; //assign c_8out3 assign {c_8out7, add_8bit[7:4]} = {1'b0, src_aor_cnst[7:4]} + {1'b0, src_pqri[7:4]} + {4'b0, c_8out3}; // notice that both inputs and outputs of the adder are being selected below. // making ed_blk_cp high priority kind of negates the origional idea of making the // decodes fast here --- course when all is included this can't be too fast. // Just note for syntheses that this is a slow path that could be improved with some thought. // assign {alu8_cry, alu8_hcry, alu8_out, src_pqri, c_8in0 }= ed_blk_cp ? {c_8out7,c_8out3, add_8bit, ~src_pqr20, 1'h1} : //CPI CPIR CPD CPDR {14{ir2[7:3]==5'b10000}} & ({c_8out7,c_8out3, add_8bit, src_pqr20, 1'b0} ) |// a+src {14{ir2[7:3]==5'b10001}} & ({c_8out7,c_8out3, add_8bit, src_pqr20, cf} ) |// a+src+cf {14{ir2[7:3]==5'b10010}} & ({c_8out7,c_8out3, add_8bit, ~src_pqr20, 1'h1} ) |// a-src {14{ir2[7:3]==5'b10011}} & ({c_8out7,c_8out3, add_8bit, ~src_pqr20, ~cf } ) |// a-src-cf {14{ir2[7:3]==5'b10100}} & ({1'b0 ,1'b1 , ar & src_pqr, src_pqr20, 1'b0} ) |// a&src {14{ir2[7:3]==5'b10101}} & ({1'b0 ,1'b0 , ar ^ src_pqr, src_pqr20, 1'b0} ) |// a^src {14{ir2[7:3]==5'b10110}} & ({1'b0 ,1'b0 , ar | src_pqr, src_pqr20, 1'b0} ) |// a|src {14{ir2[7:3]==5'b10111}} & ({c_8out7,c_8out3, add_8bit, src_pqr20, 1'h1}) |// a-src {14{(ir2[7:6]==2'b00)& ~ir2[0] }}& ({ cf,c_8out3, add_8bit, src_pqr53, 1'h1}) |// inc_r main {14{(ir2[7:6]==2'b00)& ir2[0] }}& ({ cf,c_8out3, add_8bit, src_pqr53, 1'h0}) |// dec_r {14{(ir2[7:6]==2'b01) }}& ({c_8out7,c_8out3, add_8bit, ~a, 1'h1}) ;// ed44 -a // do some hand decoding here // ADDsHL_BC = 'h09, DECsBC = 'h0B, INCsBC = 'h03 compair with {ir2[7:6],ir2[3:0]} // ADDsHL_DE = 'h19, DECsDE = 'h1B INCsDE = 'h13 ED_SBCsHL_REG = 6'b01__0010 // ADDsHL_HL = 'h29, DECsHL = 'h2B INCsHL = 'h23 ED_ADCsHL_REG = 6'b01__1010 // ADDsHL_SP = 'h39, DECsSP = 'h3B INCsSP = 'h33 // by inspection just use ir2[3:0] - i guess in a pinch we do't need ir2[2] = but let the // synthesizer figure that out. - it should be able to. // // ---------------- 16 bit adder with bit 11 carrry out and bit 8 carry in ------------------ // assign add16_ofl = (src_a[15] == src_b[15]) & (src_a[15] != add16[15]); assign {c_16out7, add16[7:0]} = {1'b0, src_a[7:0]} + {1'b0, src_b[7:0] } + {8'b0, c_16in0}; assign {c_16out11, add16[11:8]} = {1'b0, src_a[11:8]} + {1'b0, src_b[11:8] } + {4'b0, c_16out7}; assign {c_16out15, add16[15:12]} = {1'b0, src_a[15:12]} + {1'b0, src_b[15:12]} + {4'b0, c_16out11}; assign { src_a, src_b, c_16in0} = {17{ir2[3:0] == 4'h9}} & {src_dblhr, src_dbl ,1'b0 } | //ADD {17{ir2[3:0] == 4'hb}} & {16'hffff , src_dbl ,1'b0 } | //DEC {17{ir2[3:0] == 4'h3}} & {16'h0001 , src_dbl ,1'b0 } | //INC {17{ir2[3:0] == 4'h2}} & {src_dblhr, ~src_dbl , ~cf } | //SBC {17{ir2[3:0] == 4'ha}} & {src_dblhr, src_dbl , cf } ; //ADC //-------------------------- sh alu -------------------------------------------------- // shift insructions. Think of these as 8 shift types: // RLC RL RRC RR SLA SLL SRA SRL The SLL types appear to be undocumented -- but possibly used // in assembly code as they appear to have some utility - and by all accounts operate reliably. // The first four are implemented in a single byte inaruction . (A <= sh_op A ) // All 8 are implemented in the CB group with all registers as potential sources (and dests). // if dd_grp or fd_grp is prefix..... source is always the memory. This is undocumented - but // may be a useful hint for simplyfing the total machine. Destination registers // (if any) get a copy of the updated memory location (This is also true of the bit set and // clear instructions in the cb_grp. assign {sh_cry, sh_alu} = {9{ir2[5:3]==3'b000}} & {sh_src, sh_src[7] } | //RLC {9{ir2[5:3]==3'b001}} & {sh_src[0], sh_src[0], sh_src[7:1]} | // RRC {9{ir2[5:3]==3'b010}} & {sh_src, cf } | //RL {9{ir2[5:3]==3'b011}} & {sh_src[0], cf, sh_src[7:1] } | // RR {9{ir2[5:3]==3'b100}} & {sh_src, 1'b0} | //SLA {9{ir2[5:3]==3'b101}} & {sh_src[0], sh_src[7], sh_src[7:1]} | //SRA {9{ir2[5:3]==3'b110}} & {sh_src, 1-b1} | //SLL {9{ir2[5:3]==3'b111}} & {sh_src[0], 1'b0, sh_src[7:1]} ; //SRL // shift insts assign sh_alu_act = ir2[9:6] == 4'b0100; //CB_RLC = 7'b01_00_000, // these must be compaired with ir2[9:3] //CB_RRC = 7'b01_00_001, // these must be compaired with ir2[9:3] //CB_RL = 7'b01_00_010, // these must be compaired with ir2[9:3] //CB_RR = 7'b01_00_011, // these must be compaired with ir2[9:3] //CB_SLA = 7'b01_00_100, // these must be compaired with ir2[9:3] //CB_SRA = 7'b01_00_101, // these must be compaired with ir2[9:3] //CB_SLL = 7'b01_00_110, // these must be compaired with ir2[9:3] //CB_SRL = 7'b01_00_111, // these must be compaired with ir2[9:3] //---------------------------- bit test alu --------------------------------------- // bit test insts //CB_BIT = 4'b01_01, // these must be compaired with ir2[9:6] //CB_RES = 4'b01_10, // these must be compaired with ir2[9:6]assign //CB_SET = 4'b01_11, // these must be compaired with ir2[9:6] assign bit_alu_act = ir2[9:6] == CB_BIT | ir2[9:6] == CB_RES | ir2[9:6] == CB_RES ; wire bit_decode = {8{ir2[5:3] == 3'h0}} & 8'h01 | {8{ir2[5:3] == 3'h1}} & 8'h02 | {8{ir2[5:3] == 3'h2}} & 8'h04 | {8{ir2[5:3] == 3'h3}} & 8'h08 | {8{ir2[5:3] == 3'h4}} & 8'h10 | {8{ir2[5:3] == 3'h5}} & 8'h20 | {8{ir2[5:3] == 3'h6}} & 8'h40 | {8{ir2[5:3] == 3'h7}} & 8'h80 ; assign bit_alu = {8{ir2[9:6] == CB_BIT}} & ( sh_src & bit_decode) | {8{ir2[9:6] == CB_RES}} & ( sh_src & ~bit_decode) | {8{ir2[9:6] == CB_RES}} & ( shPsrc | bit_decode) ; //------------ dec bc alu --------------------------------------------- //exec_decbc; these are all we know (in general) //exec_decb; assign decc_alu = cr + 8'hff ; assign decb_alu = br + ( exec_decb ? 8'hff : // just dec b if io blk move cr_eq0 ? 8'hff : // cry out if c in this case 8'h00 ); // only dec c reg this tick // ------------------ daa alu ------------------------------------------------------- // the documentation does not cover all cases here -- only those that matter (i suppose). // ( documentation assumes you are operating with 2 daa'd numbers -- but of course the // ar can contain many values that don't fit that assumption when this instruction is executed. // Any arbitrary instruction test may test un-documented cases. // // this leaves me to guess what the actual logic is - and how to match it. // So I am doing that -- see what happens. If an instruction test breaks this... I should be // able to fix it easily. // wire [3:0] ls_nbl = (!nf & hf) ? 4'h6: (!nf & (ar[3:0] > 4'h9)) ? 4'h6: (nf & hf ) ? 4'ha: 4'h0; wire [4:0] ms_nbl = (!nf & cf) ? 5'h16: // includes new cry (!nf & (ar[3:0] > 4'h9)) ? 5'h16: (!nf & (ar[3:0] == 4'h9) & (ar[3:0] > 4'h9)) ? 5'h16: (nf & !cf & hf ) ? 5'h0f: (nf & cf & !hf ) ? 5'h1a: (nf & cf & hf ) ? 5'h19: 5'h00; assign {daa_cry, daa_alu} = { ms_nbl[4], {ar + { ms_nbl[3:0], ls_nbl}} } ; //-------1---------2---------3--------State Machines-------6---------7---------8---------9--------0 // update ar assign upd_a_alu8 = ADDsA_B == ir2 | SUBsB == ir2 | ANDsB == ir2 | ORsB == ir2 | ADDsA_C == ir2 | SUBsC == ir2 | ANDsC == ir2 | ORsC == ir2 | ADDsA_D == ir2 | SUBsD == ir2 | ANDsD == ir2 | ORsD == ir2 | ADDsA_E == ir2 | SUBsE == ir2 | ANDsE == ir2 | ORsE == ir2 | ADDsA_H == ir2 | SUBsH == ir2 | ANDsH == ir2 | ORsH == ir2 | ADDsA_L == ir2 | SUBsL == ir2 | ANDsL == ir2 | ORsL == ir2 | ADDsA_6HL7 == ir2 | SUBs6HL7 == ir2 | ANDs6HL7 == ir2 | ORs6HL7 == ir2 | ADDsA_A == ir2 | SUBsA == ir2 | ANDsA == ir2 | ORsA == ir2 | ADCsA_B == ir2 | SBCsB == ir2 | XORsB == ir2 | ADCsA_C == ir2 | SBCsC == ir2 | XORsC == ir2 | INCsA == ir2 | ADCsA_D == ir2 | SBCsD == ir2 | XORsD == ir2 | DECsA == ir2 | ADCsA_E == ir2 | SBCsE == ir2 | XORsE == ir2 | ADCsA_H == ir2 | SBCsH == ir2 | XORsH == ir2 | ADCsA_L == ir2 | SBCsL == ir2 | XORsL == ir2 | ADCsA_6HL7 == ir2 | SBCs6HL7 == ir2 | XORs6HL7 == ir2 | ADCsA_A == ir2 | SBCsA == ir2 | XORsA == ir2 | ADDsA_N == ir2 | // ADD A,N ; C6 XX ADDsA_6HL7 = 'h86 ADCsA_N == ir2 | // ADC A,N ; CE XX ADCsA_6HL7 = 'h8E SUBsN == ir2 | // SUB N ; D6 XX SUBs6HL7 = 'h96 SBCsA_N == ir2 | // SBC A,N ; DE XX ANDsN == ir2 | // AND N ; E6 XX XORsN == ir2 | // XOR N ; EE XX ORsN == ir2 ; // OR N ; F6 XX assign up_a_sh_alu = RLCA == ir2 | // RLCA ; 07 RRCA == ir2 | // RRCA ; 0F RRA == ir2 | // RRA ; 1F RLA == ir2 ; // RLA ; 17 assign up_a_src_pqr = LDsA_B == ir2 | // LD A,B ; 78 LDsA_C == ir2 | // LD A,C ; 79 LDsA_D == ir2 | // LD A,D ; 7A LDsA_E == ir2 | // LD A,E ; 7B LDsA_H == ir2 | // LD A,H ; 7C LDsA_L == ir2 | // LD A,L ; 7D LDsA_6HL7 == ir2 | // LD A,(HL) ; 7E LDsA_A == ir2 ; // LD A,A ; 7F assign up_a_n = LDsA_N == ir2 | // LD A,N ; 3E XX LDsA_6BC7 == ir2 | // LD A,(BC) ; 0A LDsA_6DE7 == ir2 | // LD A,(DE) ; 1A LDsA_6NN7 == ir2 | // LD A,(NN) ; 3A XX XX INsA_6N7 == ir2 | // IN A,(N) ; DB XX (ED_INsREG_6C7 == {ir2[7:6],ir2[2:0]}) & (ir2[5:3] == REG8_A) ; //EXsAF_AFp = 10'h08,// EX AF,AF' ; 08 //EXX = 10'hD9,// EXX ; D9 //DAA = 10'h27,// DAA ; 27 //CPL = 10'h2F,// CPL ; 2F a <= ~a //POPsAF = 10'hF1,// POP AF ; F1 // don't forget these beauties not affected by prefixes //ED_RRD = 'h67// RRD ; compair with {ir2[9:6],ir2[3:0]} all //ED_RLD = 'h6F// RLD ; ED 6F nibble roates A (HL) //ED_NEG = 5'b01___100, // A<= -A compair with {ir2[9:6],ir2[2:0]} //------------------------------- ar ------------------------------------------ assign upd_ar = upd_a_alu8 | up_a_sh_alu | up_a_src_pqr | up_a_n | ir2 == EXsAF_AFp | ir2 == EXX | ir2 == DAA | ir2 == CPL | ir2 == POPsAF | ir2[2:0] == REG8_A & bit_alu_act | ir2[2:0] == REG8_A & sh_alu_act | {ir2[9:6], ir2[3:0]} == ED_RRD | {ir2[9:6], ir2[2:0]} == ED_NEG | ir2 == ED_LDsA_I ; always @(posedge clk) begin if (upd_a_alu8 & exec_ir2) ar <= alu8_out; if (up_a_sh_alu & exec_ir2) ar <= sh_alu; if (up_a_src_pqr & exec_ir2) ar <= src_pqr; if (up_a_n & exec_ir2) ar <= nn[7:0]; if (ir2 == EXsAF_AFp & exec_ir2) ar <= ap; if (ir2 == EXX & exec_ir2) ar <= ap; if (ir2 == DAA & exec_ir2) ar <= daa_alu; if (ir2 == CPL & exec_ir2) ar <= ~ar; if (ir2 == POPsAF & exec_ir2) ar <= nn[15:8]; if (ir2[2:0] == REG8_A & bit_alu_act & exec_ir2) ar <= bit_alu; if (ir2[2:0] == REG8_A & sh_alu_act & exec_ir2) ar <= sh_alu; if ({ir2[9:6], ir2[3:0]} == ED_RRD & exec_ir2) ar[3:0] <= nn[3:0]; if ({ir2[9:6], ir2[3:0]} == ED_RLD & exec_ir2) ar[3:0] <= nn[7:4]; if ({ir2[9:6], ir2[2:0]} == ED_NEG & exec_ir2) ar <= alu8_out; // ED44 this done by alu8 for flags if (ir2 == ED_LDsA_I & exec_ir2) ar <= ir2 ; end // update br //assign upd_b_decbc = // ED_LDI == ir2 | // LDI ; ED A0 // ED_CPI == ir2 | // CPI ; ED A1 // ED_LDD == ir2 | // LDD ; ED A8 // ED_CPD == ir2 | // CPD ; ED A9 // ED_LDIR == ir2 | // LDIR ; ED B0 // ED_CPIR == ir2 | // CPIR ; ED B1 // ED_LDDR == ir2 | // LDDR ; ED B8 // ED_CPDR == ir2 ;// CPDR ; ED B9 //assign eb_io = // ED_INI == ir2 | // INI ; ED A2 // ED_IND == ir2 | // IND ; ED AA // ED_OUTD == ir2 | // OUTD ; ED AB // ED_OUTI == ir2 | // OUTI ; ED A3 // ED_INIR == ir2 | // INIR ; ED B2 // ED_OTIR == ir2 | // OTIR ; ED B3 // ED_INDR == ir2 | // INDR ; ED BA // ED_OTDR == ir2 ; // OTDR ; ED BB assign upd_b_alu8 = INCsB == ir2 |// INC B ; 04 DECsB == ir2 ;// DEC B ; 05 assign up_b_src_pqr = LDsB_B == ir2 |// LD B,B ; 40 LDsB_C == ir2 |// LD B,C ; 41 LDsB_D == ir2 |// LD B,D ; 42 LDsB_E == ir2 |// LD B,E ; 43 LDsB_H == ir2 |// LD B,H ; 44 LDsB_L == ir2 |// LD B,L ; 45 LDsB_6HL7 == ir2 |// LD B,(HL) ; 46 LDsB_A == ir2 ;// LD B,A ; 47 assign up_b_add16 = INCsBC == ir2 |// INC BC ; 03 DECsBC == ir2 ;// DEC BC ; 0B //LDsBC_nn = 10'h01,// LD BC,NN ; 01 XX XX //POPsBC = 10'hC1,// POP BC ; C1 //EXX = 10'hD9,// EXX ; D9 //LDsB_N = 10'h06,// LD B,N ; 06 XX //DJNZs$t2 = 10'h10,// DJNZ $+2 ; 10 XX //pre dec br //ED_RRD = 'h67// RRD ; ED 67 nibble roates A HL //ED_RLD = 'h6F// RLD ; ED 6F nibble roates A HL //ED_INsREG_6C7 = 5'b01___000,// compair with {ir2[7:6],ir2[2:0]} really (BCio) //------------------------------- br ----------------------------------------- assign upd_br = upd_b_alu8 | up_b_src_pqr | up_b_add16 | LDsBC_NN == ir2 | POPsBC == ir2 | EXX == ir2 | LDsB_N == ir2 | ir2[2:0] == REG8_B & bit_alu_act | ir2[2:0] == REG8_B & sh_alu_act | DJNZs$t2 == ir2 | (ED_INsREG_6C7 == {ir2[7:6],ir2[2:0]}) & (ir2[5:3] == REG8_B); always @(posedge clk) begin if ( upd_b_alu8 & exec_ir2) br <= alu8_out; if ( up_b_src_pqr & exec_ir2) br <= src_pqr; if ( up_b_add16 & exec_ir2) br <= add16[15:8]; if ( LDsBC_NN == ir2 & exec_ir2) br <= nn[15:8]; if ( POPsBC == ir2 & exec_ir2) br <= nn[15:8]; if ( EXX == ir2 & exec_ir2) br <= bp; if ( LDsB_N == ir2 & exec_ir2) br <= nn[7:0]; if (ir2[2:0] == REG8_B & bit_alu_act & exec_ir2) br <= bit_alu; if (ir2[2:0] == REG8_B & sh_alu_act & exec_ir2) br <= sh_alu; if ( DJNZs$t2 == ir2 & exec_ir2) br <= br + 8'hff; // use seperate adder here as no flags // change -- we need br==0. for now // use |br. If we need more speed add // a ff. if (exec_decb | exec_decbc) br <= decb_alu; if ( (ED_INsREG_6C7 == {ir2[7:6],ir2[2:0]}) & (ir2[5:3] == REG8_B) & exec_ir2 ) br <= nn[7:0]; end // update cr assign up_c_add16 = INCsBC == ir2 |// INC BC ; 03 DECsBC == ir2 ;// DEC BC ; 0B, assign upd_c_alu8 = INCsC == ir2 |// INC C ; 0C DECsC == ir2 ;// DEC C ; 0D assign up_c_src_pqr = LDsC_B == ir2 |// LD C,B ; 48 LDsC_C == ir2 |// LD C,C ; 49 LDsC_D == ir2 |// LD C,D ; 4A LDsC_E == ir2 |// LD C,E ; 4B LDsC_H == ir2 |// LD C,H ; 4C LDsC_L == ir2 |// LD C,L ; 4D LDsC_6HL7 == ir2 |// LD C,(HL) ; 4E LDsC_A == ir2 ;// LD C,A ; 4F //LDsC_N == ir2 |// LD C,N ; 0E XX //LDsBC_NN = 10'h01,// LD BC,NN ; 01 XX XX //POPsBC = 10'hC1,// POP BC ; C1 //EXX = 10'hD9,// EXX ; D9 //ED_INsREG_6C7 = 5'b01___000,// compair with {ir2[7:6],ir2[2:0]} really (BCio) //------------------------------- cr ----------------------------------------- assign upd_cr = upd_c_alu8 | up_c_src_pqr | up_c_add16 | LDsBC_NN == ir2 | POPsBC == ir2 | EXX == ir2 | LDsC_N == ir2 | ir2[2:0] == REG8_C & bit_alu_act | ir2[2:0] == REG8_C & sh_alu_act | (ED_INsREG_6C7 == {ir2[7:6],ir2[2:0]}) & (ir2[5:3] == REG8_C); always @(posedge clk) begin if ( upd_c_alu8 & exec_ir2) cr <= alu8_out; if ( up_c_src_pqr & exec_ir2) cr <= src_pqr; if ( up_c_add16 & exec_ir2) cr <= add16[7:0]; if ( LDsBC_NN == ir2 & exec_ir2) cr <= nn[7:0]; if ( POPsBC == ir2 & exec_ir2) cr <= nn[7:0]; if ( EXX == ir2 & exec_ir2) cr <= cp; if ( LDsC_N == ir2 & exec_ir2) cr <= nn[7:0]; if (ir2[2:0] == REG8_C & bit_alu_act & exec_ir2) cr <= bit_alu; if (ir2[2:0] == REG8_C & sh_alu_act & exec_ir2) cr <= sh_alu; if ( exec_decbc) cr <= decc_alu; if ((ED_INsREG_6C7 == {ir2[7:6],ir2[2:0]}) & (ir2[5:3] == REG8_C) & exec_ir2) cr <= nn[7:0]; end // update dr assign up_d_add16 = INCsDE == 10'h13 | // INC DE ; 13 DECsDE == 10'h1B ; // DEC DE ; 1B assign upd_d_alu8 = INCsD == 10'h14 | // INC D ; 14 DECsD == 10'h15 ; // DEC D ; 15 assign up_d_src_pqr = LDsD_B == ir2 | //LD D,B ; 50 LDsD_C == ir2 | //LD D,C ; 51 LDsD_D == ir2 | //LD D,D ; 52 LDsD_E == ir2 | //LD D,E ; 53 LDsD_H == ir2 | //LD D,H ; 54 LDsD_L == ir2 | //LD D,L ; 55 LDsD_6HL7 == ir2 | //LD D,(HL) ; 56endmodule LDsD_A == ir2 ; //LD D,A ; 57 //LDsD_N = 10'h16,// LD D,N ; 16 XX //LDsDE_NN = 10'h11,// LD DE,NN ; 11 XX XX //POPsDE = 10'hD1,// POP DE ; D1 //EXX = 10'hD9,// EXX ; D9 //EXsDE_HL = 10'hEB,// EX DE,HL ; EB //ED_INsREG_6C7 = 5'b01___000,// compair with {ir2[7:6],ir2[2:0]} really (BCio) //---------------------------------- dr ------------------------------------ assign upd_dr = upd_d_alu8 | up_d_src_pqr | up_d_add16 | LDsDE_NN == ir2 | POPsDE == ir2 | EXX == ir2 | EXsDE_HL == ir2 | LDsD_N == ir2 | ir2[2:0] == REG8_D & bit_alu_act | ir2[2:0] == REG8_D & sh_alu_act | (ED_INsREG_6C7 == {ir2[7:6],ir2[2:0]}) & (ir2[5:3] == REG8_D); always @(posedge clk) begin if ( upd_d_alu8 & exec_ir2) dr <= alu8_out; if ( up_d_src_pqr & exec_ir2) dr <= src_pqr; if ( up_d_add16 & exec_ir2) dr <= add16[15:8]; if ( LDsDE_NN == ir2 & exec_ir2) dr <= nn[15:8]; if ( POPsDE == ir2 & exec_ir2) dr <= nn[15:8]; if ( EXX == ir2 & exec_ir2) dr <= dp; if ( EXsDE_HL == ir2 & exec_ir2) dr <= hr; if ( LDsD_N == ir2 & exec_ir2) dr <= nn[7:0]; if (ir2[2:0] == REG8_D & bit_alu_act & exec_ir2) dr <= bit_alu; if (ir2[2:0] == REG8_D & sh_alu_act & exec_ir2) dr <= sh_alu; if ((ED_INsREG_6C7 == {ir2[7:6],ir2[2:0]}) & (ir2[5:3] == REG8_D) & exec_ir2) dr <= nn[7:0]; end // update er assign up_e_add16 = INCsDE == ir2 |// INC DE ; 13 DECsDE == ir2 ;// DEC DE ; 1B assign upd_e_alu8 = INCsE == ir2 |// INC E ; 1C DECsE == ir2 ;// DEC E ; 1D assign up_e_src_pqr = LDsE_B == ir2 |// LD E,B ; 58 LDsE_C == ir2 |// LD E,C ; 59 LDsE_D == ir2 |// LD E,D ; 5A LDsE_E == ir2 |// LD E,E ; 5B LDsE_H == ir2 |// LD E,H ; 5C LDsE_L == ir2 |// LD E,L ; 5D LDsE_6HL7 == ir2 |// LD E,(HL) ; 5E LDsE_A == ir2 ;// LD E,A ; 5F //LDsE_N = 10'h1E,// LD E,N ; 1E XX //LDsDE_NN = 10'h11,// LD DE,NN ; 11 XX XX //POPsDE = 10'hD1,// POP DE ; D1 //EXX = 10'hD9,// EXX ; D9 //EXsDE_HL = 10'hEB,// EX DE,HL ; EB //ED_INsREG_6C7 = 5'b01___000,// compair with {ir2[7:6],ir2[2:0]} really (BCio) //---------------------------------- er ------------------------------------ assign upd_er = upd_e_alu8 | up_e_src_pqr | up_e_add16 | LDsDE_NN == ir2 | POPsDE == ir2 | EXX == ir2 | EXsDE_HL == ir2 | LDsD_N == ir2 | ir2[2:0] == REG8_E & bit_alu_act | ir2[2:0] == REG8_E & sh_alu_act | (ED_INsREG_6C7 == {ir2[7:6],ir2[2:0]}) & (ir2[5:3] == REG8_E); always @(posedge clk) begin if ( upd_e_alu8 & exec_ir2) er <= alu8_out; if ( up_e_src_pqr & exec_ir2) er <= src_pqr; if ( up_e_add16 & exec_ir2) er <= add16; if ( LDsDE_NN == ir2 & exec_ir2) er <= nn[7:0]; if ( POPsDE == ir2 & exec_ir2) er <= nn[7:0]; if ( EXX == ir2 & exec_ir2) er <= ep; if ( EXsDE_HL == ir2 & exec_ir2) er <= hr; if ( LDsE_N == ir2 & exec_ir2) er <= nn[7:0]; if (ir2[2:0] == REG8_E & bit_alu_act & exec_ir2) er <= bit_alu; if (ir2[2:0] == REG8_E & sh_alu_act & exec_ir2) er <= sh_alu; if ((ED_INsREG_6C7 == {ir2[7:6],ir2[2:0]}) & (ir2[5:3] == REG8_E) & exec_ir2) er <= nn[7:0]; end // update hr assign up_h_add16 = ADDsHL_BC == ir2 | // ADD HL,BC ; 09 ADDsHL_DE == ir2 | // ADD HL,DE ; 19 ADDsHL_HL == ir2 | // ADD HL,HL ; 29 ADDsHL_SP == ir2 | // ADD HL,SP ; 39 INCsHL == ir2 | // INC HL ; 23 DECsHL == ir2 ; // DEC HL ; 2B assign upd_h_alu8 = INCsH == ir2 | // INC H ; 24 DECsH == ir2 ; // DEC H ; 25 assign upd_h_src_pqr = LDsH_B == ir2 | // LD H,B ; 60 LDsH_C == ir2 | // LD H,C ; 61 LDsH_D == ir2 | // LD H,D ; 62 LDsH_E == ir2 | // LD H,E ; 63 LDsH_H == ir2 | // LD H,H ; 64 LDsH_L == ir2 | // LD H,L ; 65 LDsH_6HL7 == ir2 | // LD H,(HL) ; 66 LDsH_A == ir2 ; // LD H,A ; 67 //ED_INsREG_6C7 = 5'b01___000,// compair with {ir2[7:6],ir2[2:0]} really (BCio) //POPsHL = 10'hE1,// POP HL ; E1 //EXs6SP7_HL = 10'hE3,// EX (SP),HL ; E3 //LDsHL_NN = 10'h21,// LD HL,NN ; 21 XX XX //LDsHL_6NN7 = 10'h2A,// LD HL,(NN) ; 2A XX XX //LDsH_N = 10'h26,// LD H,N ; 26 XX // only these are not affected by dd and fd prefixes //EXsDE_HL = 10'hEB,// EX DE,HL ; EB //EXX = 10'hD9,// EXX ; D9 //---------------------------------- hr ------------------------------------ // we just check hr and lr - the prefixes for use of ix and iy imply that something // pretty strange has to happen for a hazard related to use of those registers. We can // assume upd hr impies upd ix and iy without adverse timing consequences. // assign upd_hr = upd_h_alu8 | up_h_src_pqr | up_h_add16 | LDsHL_NN == ir2 | LDsHL_6NN7== ir2 | POPsHL == ir2 | EXX == ir2 | EXsDE_HL == ir2 | LDsH_N == ir2 | ir2[2:0] == REG8_H & bit_alu_act | ir2[2:0] == REG8_H & sh_alu_act | (ED_INsREG_6C7 == {ir2[7:6],ir2[2:0]}) & (ir2[5:3] == REG8_H); wire exec_hlir2 = exec_ir2 & !(dd_grp | fd_grp); always @(posedge clk) begin if ( upd_h_alu8 & exec_hlir2) hr <= alu8_out; if ( up_h_src_pqr & exec_hlir2) hr <= src_pqr; if ( up_h_add16 & exec_hlir2) hr <= add16[15:8]; if ( LDsHL_NN == ir2 & exec_hlir2) hr <= nn[15:8]; if ( LDsHL_6NN7== ir2 & exec_hlir2) hr <= nn[15:8]; if ( POPsHL == ir2 & exec_hlir2) hr <= nn[15:8]; if ( EXs6SP7_HL== ir2 & exec_hlir2) hr <= nn[15:8]; if ( EXX == ir2 & exec_ir2) hr <= hp; if ( EXsDE_HL == ir2 & exec_ir2) hr <= dr; if ( LDsH_N == ir2 & exec_hlir2) hr <= nn[7:0]; if (ir2[2:0] == REG8_H & bit_alu_act & exec_hlir2) hr <= bit_alu; if (ir2[2:0] == REG8_H & sh_alu_act & exec_hlir2) hr <= sh_alu; if ((ED_INsREG_6C7 == {ir2[7:6],ir2[2:0]}) & (ir2[5:3] == REG8_H) & exec_ir2) hr <= nn[7:0]; end // update lr assign up_l_add16 = ADDsHL_BC == ir2 |// ADD HL,BC ; 09 ADDsHL_DE == ir2 |// ADD HL,DE ; 19 ADDsHL_HL == ir2 |// ADD HL,HL ; 29 ADDsHL_SP == ir2 |// ADD HL,SP ; 39 INCsHL == ir2 |// INC HL ; 23 DECsHL == ir2 ;// DEC HL ; 2B assign upd_l_alu8 = INCsL == ir2 |// INC L ; 2C DECsL == ir2 ;// DEC L ; 2D assign upd_l_src_pqr = LDsL_B == ir2 |// LD L,B ; 68 LDsL_C == ir2 |// LD L,C ; 69 LDsL_D == ir2 |// LD L,D ; 6A LDsL_E == ir2 |// LD L,E ; 6B LDsL_H == ir2 |// LD L,H ; 6C LDsL_L == ir2 |// LD L,L ; 6D LDsL_6HL7 == ir2 |// LD L,(HL) ; 6E LDsL_A == ir2 ;// LD L,A ; 6F //EXX = 10'hD9,// EXX ; D9 //POPsHL = 10'hE1,// POP HL ; E1 //EXs6SP7_HL = 10'hE3,// EX (SP),HL ; E3 //EXsDE_HL = 10'hEB,// EX DE,HL ; EB //LDsHL_NN = 10'h21,// LD HL,NN ; 21 XX XX //LDsHL_6NN7 = 10'h2A,// LD HL,(NN) ; 2A XX XX //LDsL_N = 10'h2E,// LD L,N ; 2E XX //ED_INsREG_6C7 //---------------------------------- lr ------------------------------------ assign upd_lr = upd_l_alu8 | up_l_src_pqr | up_l_add16 | LDsHL_NN == ir2 | LDsHL_6NN7== ir2 | POPsHL == ir2 | EXX == ir2 | EXsDE_HL == ir2 | LDsL_N == ir2 | ir2[2:0] == REG8_L & bit_alu_act | ir2[2:0] == REG8_L & sh_alu_act | (ED_INsREG_6C7 == {ir2[7:6],ir2[2:0]}) & (ir2[5:3] == REG8_L); always @(posedge clk) begin if ( upd_l_alu8 & exec_hlir2) lr <= alu8_out; if ( up_l_src_pqr & exec_hlir2) lr <= src_pqr; if ( up_l_add16 & exec_hlir2) lr <= add16[7:0]; if ( LDsHL_NN == ir2 & exec_hlir2) lr <= nn[7:0]; if ( LDsHL_6NN7== ir2 & exec_hlir2) lr <= nn[7:0]; if ( POPsHL == ir2 & exec_hlir2) lr <= nn[7:0]; if ( EXs6SP7_HL== ir2 & exec_hlir2) lr <= nn[7:0]; if ( EXX == ir2 & exec_ir2) lr <= lp; if ( EXsDE_HL == ir2 & exec_ir2) lr <= er; if ( LDsL_N == ir2 & exec_hlir2) lr <= nn[7:0]; if (ir2[2:0] == REG8_L & bit_alu_act & exec_hlir2) lr <= bit_alu; if (ir2[2:0] == REG8_L & sh_alu_act & exec_hlir2) lr <= sh_alu; if ((ED_INsREG_6C7 == {ir2[7:6],ir2[2:0]}) & (ir2[5:3] == REG8_L) & exec_ir2) lr <= nn[7:0]; end //------------------------ ixr --------------------------------------------- wire exec_ixir2 = exec_ir2 & dd_grp; always @(posedge clk) begin if ( upd_l_alu8 & exec_ixir2) ixr[7:0] <= alu8_out; if ( up_l_src_pqr & exec_ixir2) ixr[7:0] <= src_pqr; if ( up_l_add16 & exec_ixir2) ixr[7:0] <= add16[7:0]; if ( LDsHL_NN == ir2 & exec_ixir2) ixr[7:0] <= nn[7:0]; if ( LDsHL_6NN7== ir2 & exec_ixir2) ixr[7:0] <= nn[7:0]; if ( POPsHL == ir2 & exec_ixir2) ixr[7:0] <= nn[7:0]; if ( EXs6SP7_HL== ir2 & exec_ixir2) ixr[7:0] <= nn[7:0]; if ( LDsL_N == ir2 & exec_ixir2) ixr[7:0] <= nn[7:0]; if (ir2[2:0] == REG8_L & bit_alu_act & exec_ixir2) ixr[7:0] <= bit_alu; if (ir2[2:0] == REG8_L & sh_alu_act & exec_ixir2) ixr[7:0] <= sh_alu; end always @(posedge clk) begin if ( upd_h_alu8 & exec_ixir2) ixr[15:8] <= alu8_out; if ( up_h_src_pqr & exec_ixir2) ixr[15:8] <= src_pqr; if ( up_h_add16 & exec_ixir2) ixr[15:8] <= add16[15:8]; if ( LDsHL_NN == ir2 & exec_ixir2) ixr[15:8] <= nn[15:8]; if ( LDsHL_6NN7== ir2 & exec_ixir2) ixr[15:8] <= nn[15:8]; if ( POPsHL == ir2 & exec_ixir2) ixr[15:8] <= nn[15:8]; if ( EXs6SP7_HL== ir2 & exec_ixir2) ixr[15:8] <= nn[15:8]; if ( LDsH_N == ir2 & exec_ixir2) ixr[15:8] <= nn[7:0]; if (ir2[2:0] == REG8_H & bit_alu_act & exec_ixir2) ixr[15:8] <= bit_alu; if (ir2[2:0] == REG8_H & sh_alu_act & exec_ixir2) ixr[15:8] <= sh_alu; end //------------------------ iyr --------------------------------------------- wire exec_iyir2 = exec_ir2 & fd_grp; always @(posedge clk) begin if ( upd_l_alu8 & exec_iyir2) iyr[7:0] <= alu8_out; if ( up_l_src_pqr & exec_iyir2) iyr[7:0] <= src_pqr; if ( up_l_add16 & exec_iyir2) iyr[7:0] <= add16[7:0]; if ( LDsHL_NN == ir2 & exec_iyir2) iyr[7:0] <= nn[7:0]; if ( LDsHL_6NN7== ir2 & exec_iyir2) iyr[7:0] <= nn[7:0]; if ( POPsHL == ir2 & exec_iyir2) iyr[7:0] <= nn[7:0]; if ( EXs6SP7_HL== ir2 & exec_iyir2) iyr[7:0] <= nn[7:0]; if ( LDsL_N == ir2 & exec_iyir2) iyr[7:0] <= nn[7:0]; if (ir2[2:0] == REG8_L & bit_alu_act & exec_iyir2) iyr[7:0] <= bit_alu; if (ir2[2:0] == REG8_L & sh_alu_act & exec_iyir2) iyr[7:0] <= sh_alu; end always @(posedge clk) begin if ( upd_h_alu8 & exec_iyir2) iyr[15:8] <= alu8_out; if ( up_h_src_pqr & exec_iyir2) iyr[15:8] <= src_pqr; if ( up_h_add16 & exec_iyir2) iyr[15:8] <= add16[15:8]; if ( LDsHL_NN == ir2 & exec_iyir2) iyr[15:8] <= nn[15:8]; if ( LDsHL_6NN7== ir2 & exec_iyir2) iyr[15:8] <= nn[15:8]; if ( POPsHL == ir2 & exec_iyir2) iyr[15:8] <= nn[15:8]; if ( EXs6SP7_HL== ir2 & exec_iyir2) iyr[15:8] <= nn[15:8]; if ( LDsH_N == ir2 & exec_iyir2) iyr[15:8] <= nn[7:0]; if (ir2[2:0] == REG8_H & bit_alu_act & exec_iyir2) iyr[15:8] <= bit_alu; if (ir2[2:0] == REG8_H & sh_alu_act & exec_iyir2) iyr[15:8] <= sh_alu; end //---------------------------- prime regiters (shadows?) ---------------- always @(posedge clk) begin if (ir2 == EXsAF_AFp & exec_ir2) begin ap <= ar; fp <= fr; end if (ir2 == EXX & exec_ir2) begin ap <= ar; fp <= fr; bp <= br; cp <= cr; dp <= dr; ep <= er; hp <= hr; lp <= lr; end end //-------------------------- flag registers ------------------------------- // This is a mess - There is in general no reasonable way to get this stuff to follow // z80 exactly. --- in some of the undocumented cases, there is not even a // guess expressed about what is actually done. In some of the other undocumented // cases, what is claimed happens is soo silly that It is hard for me to believe // it matters ( unfortunately i am far too aware that one man's garbage can be // anothers treasure --- or....., its amazing how silly // behavior (bug?) can become a feature. In any case, The attempt (at first blush) is // only to get the documented stuff right -- although if undocumented behavior // falls out, great. For exmple, I will typically update f3f and f5f with alu output - // these flags are documented as "undefined". // // some of the wierd stuff to worry about: // 16 bit ops: // the ed insts SBC ADC muck with all flags but // the ADD inst doesn't change sf zf or pvf. // and the 16 bit INC and DEC insts touch nothing // // the ED_RLD and RRD instructions muck with flags based on ar -- these operations // should be correct rleative to subsequent DAA's i suppose. // update all flags from alu8 for logic operations pv <= parity else ofl // INC and DEC same as but no cf change oh my god why? done in logic above assign upd_fr_alu8 = ADCsA_A == ir2 | ANDsA == ir2 | ORsA == ir2 | SUBsA == ir2 | DECsA == ir2 | ADCsA_B == ir2 | ANDsB == ir2 | ORsB == ir2 | SUBsB == ir2 | DECsB == ir2 | ADCsA_C == ir2 | ANDsC == ir2 | ORsC == ir2 | SUBsC == ir2 | DECsC == ir2 | ADCsA_D == ir2 | ANDsD == ir2 | ORsD == ir2 | SUBsD == ir2 | DECsD == ir2 | ADCsA_E == ir2 | ANDsE == ir2 | ORsE == ir2 | SUBsE == ir2 | DECsE == ir2 | ADCsA_H == ir2 | ANDsH == ir2 | ORsH == ir2 | SUBsH == ir2 | DECsH == ir2 | ADCsA_L == ir2 | ANDsL == ir2 | ORsL == ir2 | SUBsL == ir2 | DECsL == ir2 | ADCsA_6HL7==ir2 | ANDs6HL7 ==ir2 | ORs6HL7 ==ir2 | SUBs6HL7 ==ir2 | INCsA == ir2 | ADDsA_A == ir2 | CPsA == ir2 | SBCsA == ir2 | XORsA == ir2 | INCsB == ir2 | ADDsA_B == ir2 | CPsB == ir2 | SBCsA_6HL7==ir2 | XORsB == ir2 | INCsC == ir2 | ADDsA_C == ir2 | CPsC == ir2 | SBCsB == ir2 | XORsC == ir2 | INCsD == ir2 | ADDsA_D == ir2 | CPsD == ir2 | SBCsC == ir2 | XORsD == ir2 | INCsE == ir2 | ADDsA_E == ir2 | CPsE == ir2 | SBCsD == ir2 | XORsE == ir2 | INCsH == ir2 | ADDsA_H == ir2 | CPsH == ir2 | SBCsE == ir2 | XORsH == ir2 | INCsL == ir2 | ADDsA_L == ir2 | CPsL == ir2 | SBCsH == ir2 | XORsL == ir2 | INCs6HL7 == ir2 | ADDsA_6HL7== ir2| CPs6HL7 ==ir2 | SBCsL == ir2 | XORs6HL7 == ir2 | DECs6HL7 == ir2 | ED_NEG == {ir2[9:6],ir2[2:0]} ; //7'b1001___100, A<= -A // update h n c (f5, f3) from alu16 assign upd_fr_add16 = ADDsHL_BC == ir2 | // ADD HL,BC ; 09 ADDsHL_DE == ir2 | // ADD HL,DE ; 19 ADDsHL_HL == ir2 | // ADD HL,HL ; 29 ADDsHL_SP == ir2 ; // ADD HL,SP ; 39 // INCsBC == ir2 | // INC BC ; 03 no flag changes for these // INCsDE == ir2 | // INC DE ; 13 // INCsHL == ir2 | // INC HL ; 23 // INCsSP == ir2 ; // INC SP ; 33 // update all flags from alu16 assign upd_fr_edadd16 = ED_SBCsHL_REG == {ir2[7:6],ir2[3:0]} | // compair with {ir2[7:6],ir2[3:0]} ED_ADCsHL_REG == {ir2[7:6],ir2[3:0]} ; // compair with {ir2[7:6],ir2[3:0]} // the shifts probably muck with all flags (some operations are // guarenteed not to change certain flags ) // docs say sf and zf never change for these ops. assign upd_fr_sh = RLA == ir2 |// RLA ; 17 RLCA == ir2 |// RLCA ; 07 RRA == ir2 |// RRA ; 1F RRCA == ir2 ;// RRCA ; 0F // sf and zf do change for theses assign upd_fr_cbsh = CB_RLC == ir2[9:3] | // these must be compaired with ir2[9:3] CB_RRC == ir2[9:3] | // these must be compaired with ir2[9:3] CB_RL == ir2[9:3] | // these must be compaired with ir2[9:3] CB_RR == ir2[9:3] | // these must be compaired with ir2[9:3] CB_SLA == ir2[9:3] | // these must be compaired with ir2[9:3] CB_SRA == ir2[9:3] | // these must be compaired with ir2[9:3] CB_SLL == ir2[9:3] | // these must be compaired with ir2[9:3] CB_SRL == ir2[9:3] ; // these must be compaired with ir2[9:3] // pretty nomal stuff here //CB_BIT = 4'b01_01, // these must be compaired with ir2[9:6] // which alu? -- done from alu8 //ED_NEG = 5'b01___100, // compair with {ir2[7:6],ir2[2:0]} all A<= -A // rmw 8 types these handled by standard INC and DEC logic done. //INCs6HL7 = 'h34,// INC (HL) ; 34 //DECs6HL7 = 'h35,// DEC (HL) ; 35 // ED Block Move messyness upd_b_decbc // hf and nf <= 0 pnf<= BC==0 assign eb_blk_mv = ED_LDI == ir2 | // LDI ; ED A0 (DE++) <= (HL++) , BC-- ED_LDD == ir2 | // LDD ; ED A8 (DE--) <= (HL--) , BC-- ED_LDIR == ir2 | // LDIR ; ED B0 (DE++) <= (HL++) , BC-- Repeat til BC==0 ED_LDDR == ir2 ;// LDDR ; ED B8 (DE--) <= (HL--) , BC-- Repeat til BC==0 // only c not affected - nf<=1 ? assign ed_blk_cp = ED_CPI == ir2 | // CPI ; ED A1 A - (HL++) , BC-- ED_CPD == ir2 | // CPD ; ED A9 A - (HL--) , BC-- ED_CPIR == ir2 | // CPIR ; ED B1 A - (HL++) , BC-- repeat if(|B ED_CPDR == ir2 ;// CPDR ; ED B9 A - (HL--) , BC-- repeat if(|B // all the ed i/o muck with all flags -- wonderful cf? // use the aluoutput for the b-1 computation. // --------- eb_io //ED_INI = 'hA2// INI ; ED A2 (HL++) <- (Cio) , B-- //ED_IND = 'hAA// IND ; ED AA (HL--) <- (Cio) , B-- //ED_INIR = 'hB2// INIR ; ED B2 (HL++) <- (Cio) , B-- repeat if(|B) //ED_INDR = 'hBA// INDR ; ED BA (HL--) <- (Cio) , B-- repeat if(|B) //ED_OUTI = 'hA3// OUTI ; ED A3 (Cio) <-(HL++) , B-- //ED_OUTD = 'hAB// OUTD ; ED AB (Cio) <-(HL--) , B-- //ED_OTIR = 'hB3// OTIR ; ED B3 (Cio) <-(HL++) , B-- rpt if(|B) //ED_OTDR = 'hBB// OTDR ; ED BB (Cio) <-(HL--) , B-- rpt if(|B) //ED_INsREG_6C7 = 5'b01___000,// compair with {ir2[7:6],ir2[2:0]} really (BCio) // special problems -- lol more special problems ???? //CCF = 'h3F,// CCF ; 3F // h<=c c<=~C N<=0 F3,F5? //CPL = 'h2F,// CPL ; 2F // H<=1 N<=1 F3,F5? //DAA = 'h27,// DAA ; 27 // H<=0??? //SCF = 'h37,// SCF ; 37 //ED_RRD = 'h67// RRD ; ED 67 nibble roates A HL //ED_RLD = 'h6F// RLD ; ED 6F nibble roates A HL //ED_LDsA_I = 'h57// LD A,I ; ED 57 move I to A assign { sf, zf, f5f, hf, f3f, pvf, nf, cf} = fr; // gotta say those little ~^ operators down there worry me. Only 4 levels of xor - but jeeze // there are a lot of them. I guess in most FPGA's it doesn't matter what the op is - just // how many terms. // do we need the exe_ir2 term here? isn't it added in the hazard term anyway? assign upd_fr = exec_ir2 & ( ( upd_fr_alu8 ) | ( upd_fr_add16) | ( upd_fr_edadd16) | ( upd_fr_sh ) | ( upd_fr_cbsh ) | (CB_BIT == ir2[9:6]) | ( ed_blk_cp ) | (ED_INsREG_6C7 == {ir2[7:6],ir2[2:0]}) | (CCF == ir2 ) | (CPL == ir2 ) | (DAA == ir2 ) | (SCF == ir2 ) | (ED_RRD == ir2) | (ED_RLD == ir2) | (ED_LDsA_I == ir2) ) ; wire iff2 = 1'b0; // this is supposed to be int ff #2 which is not (yet) implmented always @(posedge clk) begin if (exec_ir2) begin if ( upd_fr_alu8 ) fr <= alu8_fr; // assembled above with 8 bit ALU if ( upd_fr_add16) fr <= {sf, zf, add16[13], c_16out11, add16[11], pvf, 1'b0, c_16out15}; if ( upd_fr_edadd16) fr <= {add16[15], ~|add16, add16[13], c_out11, add16[11], add16_ofl, ~ir2[3], c_16out15}; if ( upd_fr_sh ) fr <= {sf, zf, sh_alu[5], 1'b0, sh_alu[3], pvf, 1'b0, sh_cry}; if ( upd_fr_cbsh ) fr <= {sh_alu[7], ~|sh_alu, sh_alu[5], 1'b0, sh_alu[3], ~^sh_alu, 1'b0, sh_cry}; if (CB_BIT == ir2[9:6]) fr <={bit_alu[7], ~|bit_alu, bit_alu[5], 1'b1, //no idea why hf<=1 bit_alu[3], ~|bit_alu, 1'b0 , cf };// pvf == zf ??? if ( ed_blk_cp ) fr <= {alu8_out[7], ~|alu8_out, alu8_out[5], alu8_hcry,//std a-n stuff alu8_out[3], alu8_out[7], 1'b1, cf }; //cept nf and cf if (ED_INsREG_6C7 == {ir2[7:6],ir2[2:0]}) fr <= {nn[7], ~|nn[7:0], nn[5], 1'b0, nn[3], ~^nn[7:0], 1'b0, cf}; if (CCF == ir2 ) fr <= {sf, zf, f5f, cf, f3f, pvf, nf, ~cf}; if (CPL == ir2 ) fr <= {sf, zf, ar[5], 1'b1, ar[3], pvf, 1'b1, cf}; if (DAA == ir2 ) fr <= {daa_alu[7], ~|daa_alu, daa_alu[5], 1'b0, // hf sb (logically) 0 daa_alu[3], ~^daa_alu, nf, daa_cry }; if (SCF == ir2 ) fr <= { sf, zf, ar[5], 1'b0, ar[3], pvf, 1'b0, 1'b1 }; // very strange if (ED_RRD == ir2) fr <= { sf, ~|{ar[7:4],nn[3:0]}, ar[5], 1'b0, ar[3], ~^{ar[7:4],nn[3:0]}, 1'b0 , cf }; if (ED_RLD == ir2) fr <= { sf, ~|{ar[7:4],nn[7:4]}, ar[5], 1'b0, ar[3], ~^{ar[7:4],nn[7:4]}, 1'b0 , cf }; if (ED_LDsA_I == ir2) fr <= { ir2[7], ~|ir2, ir2[5], 1'b0, ir2[3], iff2, 1'b0, cf }; // iff2 ? end // in the case of blk_cp the update above is executed 2nd - and so these are don't cares. if (exec_decb ) fr <= {decb_alu[7], ~|decb_alu, decb_alu[5], hf, decb_alu[3], pvf, 1'b0, cf }; if (exec_decbc ) fr[5:1] <= { decb_alu[5], 1'b0, decb_alu[3], ~|decb_alu, 1'b0 }; end //----------------------- intr ----------------------------------------------------------- always @(posedge clk) begin if (( ED_LDsI_A == ir2) & exec_ir2) intr <= ar; end endmodule
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