| 1 |
2 |
bsa |
/*******************************************************************************************/
|
| 2 |
|
|
/** **/
|
| 3 |
|
|
/** COPYRIGHT (C) 2011, SYSTEMYDE INTERNATIONAL CORPORATION, ALL RIGHTS RESERVED **/
|
| 4 |
|
|
/** **/
|
| 5 |
|
|
/** data path module Rev 0.0 08/22/2010 **/
|
| 6 |
|
|
/** **/
|
| 7 |
|
|
/*******************************************************************************************/
|
| 8 |
|
|
module datapath (addr_reg_in, carry_bit, dmar_reg, dout_io_reg, dout_mem_reg, inst_reg,
|
| 9 |
|
|
intr_reg, page_reg, par_bit, sign_bit, tflg_reg, vector_int, xhlt_reg,
|
| 10 |
|
|
zero_bit, add_sel, alua_sel, alub_sel, aluop_sel, clearb, clkc, cflg_en,
|
| 11 |
|
|
data_in, di_ctl, dma_req, do_ctl, ex_af_pls, ex_bank_pls, ex_dehl_inst,
|
| 12 |
|
|
hflg_ctl, ief_ctl, imd_ctl, int_req, ivec_rd, ld_ctrl, ld_inst, ld_page,
|
| 13 |
|
|
nflg_ctl, nmi_req, page_sel, pc_sel, pflg_ctl, resetb, sflg_en, tflg_ctl,
|
| 14 |
|
|
wait_st, wr_addr, zflg_en);
|
| 15 |
|
|
|
| 16 |
|
|
input cflg_en; /* carry flag control */
|
| 17 |
|
|
input clearb; /* master (testing) reset */
|
| 18 |
|
|
input clkc; /* main cpu clock */
|
| 19 |
|
|
input dma_req; /* dma request */
|
| 20 |
|
|
input ex_af_pls; /* exchange af,af' */
|
| 21 |
|
|
input ex_bank_pls; /* exchange register bank */
|
| 22 |
|
|
input ex_dehl_inst; /* exchange de,hl */
|
| 23 |
|
|
input int_req; /* interrupt request */
|
| 24 |
|
|
input ivec_rd; /* interrupt vector enable */
|
| 25 |
|
|
input ld_ctrl; /* load control register */
|
| 26 |
|
|
input ld_inst; /* load instruction register */
|
| 27 |
|
|
input ld_page; /* load page register */
|
| 28 |
|
|
input nmi_req; /* nmi request */
|
| 29 |
|
|
input resetb; /* internal (user) reset */
|
| 30 |
|
|
input sflg_en; /* sign flag control */
|
| 31 |
|
|
input wait_st; /* wait state identifier */
|
| 32 |
|
|
input zflg_en; /* zero flag control */
|
| 33 |
|
|
input [3:0] page_sel; /* instruction decode "page" control */
|
| 34 |
|
|
input [7:0] data_in; /* read data bus */
|
| 35 |
|
|
input [`ADCTL_IDX:0] add_sel; /* address output mux control */
|
| 36 |
|
|
input [`ALUA_IDX:0] alua_sel; /* alu input a mux control */
|
| 37 |
|
|
input [`ALUB_IDX:0] alub_sel; /* alu input b mux control */
|
| 38 |
|
|
input [`ALUOP_IDX:0] aluop_sel; /* alu operation control */
|
| 39 |
|
|
input [`DI_IDX:0] di_ctl; /* data input control */
|
| 40 |
|
|
input [`DO_IDX:0] do_ctl; /* data output control */
|
| 41 |
|
|
input [`HFLG_IDX:0] hflg_ctl; /* half-carry flag control */
|
| 42 |
|
|
input [`IEF_IDX:0] ief_ctl; /* interrupt enable control */
|
| 43 |
|
|
input [`IMD_IDX:0] imd_ctl; /* interrupt mode control */
|
| 44 |
|
|
input [`NFLG_IDX:0] nflg_ctl; /* negate flag control */
|
| 45 |
|
|
input [`PCCTL_IDX:0] pc_sel; /* program counter source control */
|
| 46 |
|
|
input [`PFLG_IDX:0] pflg_ctl; /* parity/overflow flag control */
|
| 47 |
|
|
input [`TFLG_IDX:0] tflg_ctl; /* temp flag control */
|
| 48 |
|
|
input [`WREG_IDX:0] wr_addr; /* register write address bus */
|
| 49 |
|
|
output carry_bit; /* carry flag */
|
| 50 |
|
|
output dmar_reg; /* latched dma request */
|
| 51 |
|
|
output intr_reg; /* latched interrupt request */
|
| 52 |
|
|
output par_bit; /* parity flag */
|
| 53 |
|
|
output sign_bit; /* sign flag */
|
| 54 |
|
|
output tflg_reg; /* temporary flag */
|
| 55 |
|
|
output vector_int; /* int vector enable */
|
| 56 |
|
|
output xhlt_reg; /* halt exit */
|
| 57 |
|
|
output zero_bit; /* zero flag */
|
| 58 |
|
|
output [3:0] page_reg; /* instruction decode "page" */
|
| 59 |
|
|
output [7:0] inst_reg; /* instruction register */
|
| 60 |
|
|
output [7:0] dout_io_reg; /* i/o write data bus */
|
| 61 |
|
|
output [7:0] dout_mem_reg; /* memory write data bus */
|
| 62 |
|
|
output [15:0] addr_reg_in; /* processor address bus */
|
| 63 |
|
|
|
| 64 |
|
|
/*****************************************************************************************/
|
| 65 |
|
|
/* */
|
| 66 |
|
|
/* signal declarations */
|
| 67 |
|
|
/* */
|
| 68 |
|
|
/*****************************************************************************************/
|
| 69 |
|
|
wire adder_c; /* math carry */
|
| 70 |
|
|
wire adder_hc; /* math half-carry */
|
| 71 |
|
|
wire adder_ov; /* math overflow result */
|
| 72 |
|
|
wire alu_carry; /* final carry */
|
| 73 |
|
|
wire alu_hcar; /* final half-carry */
|
| 74 |
|
|
wire alu_neg; /* final negate */
|
| 75 |
|
|
wire alu_one; /* final one */
|
| 76 |
|
|
wire alu_sign; /* final sign */
|
| 77 |
|
|
wire alu_zero; /* final zero */
|
| 78 |
|
|
wire bit7, bit6, bit5, bit4; /* bit decode */
|
| 79 |
|
|
wire bit3, bit2, bit1, bit0;
|
| 80 |
|
|
wire carry_bit; /* carry flag */
|
| 81 |
|
|
wire carry_daa; /* daa carry */
|
| 82 |
|
|
wire cry_nxt; /* combined carry */
|
| 83 |
|
|
wire daa_l1, daa_l2, daa_l3, daa_l4; /* decimal adjust */
|
| 84 |
|
|
wire daa_l5, daa_h1, daa_h2, daa_h3;
|
| 85 |
|
|
wire daa_h4, daa_h5, daa_h6, daa_h7;
|
| 86 |
|
|
wire daa1, daa2, daa3, daa4, daa5;
|
| 87 |
|
|
wire daa6, daa7;
|
| 88 |
|
|
wire hcar_nxt; /* combined half-carry */
|
| 89 |
|
|
wire hi_byte; /* replicate data byte */
|
| 90 |
|
|
wire ld_m_aa, ld_m_ff, ld_m_bb, ld_m_cc; /* register loads */
|
| 91 |
|
|
wire ld_m_dd, ld_m_ee, ld_m_hh, ld_m_ll;
|
| 92 |
|
|
wire ld_a_aa, ld_a_ff, ld_a_bb, ld_a_cc;
|
| 93 |
|
|
wire ld_a_dd, ld_a_ee, ld_a_hh, ld_a_ll;
|
| 94 |
|
|
wire ld_sp, ld_ix, ld_iy;
|
| 95 |
|
|
wire ld_ii, ld_rr, ld_tmp;
|
| 96 |
|
|
wire ld_dout_io, ld_dout_mem; /* load data out */
|
| 97 |
|
|
wire ld_flag; /* load flags */
|
| 98 |
|
|
wire ld_regf; /* load register file */
|
| 99 |
|
|
wire ld_tflg; /* load temp flag */
|
| 100 |
|
|
wire logic_c; /* logic carry */
|
| 101 |
|
|
wire logic_hc; /* logic half-carry */
|
| 102 |
|
|
wire one_nxt; /* combined one */
|
| 103 |
|
|
wire par_bit; /* parity flag */
|
| 104 |
|
|
wire par_nxt; /* combined parity */
|
| 105 |
|
|
wire shft_c; /* shift carry */
|
| 106 |
|
|
wire sign_bit; /* sign flag */
|
| 107 |
|
|
wire sign_nxt; /* combined sign */
|
| 108 |
|
|
wire vector_int; /* int vector enable */
|
| 109 |
|
|
wire zero_bit; /* zero flag */
|
| 110 |
|
|
wire zero_nxt; /* combined zero */
|
| 111 |
|
|
wire [7:0] bit_mask; /* mask for bit inst */
|
| 112 |
|
|
wire [7:0] daa_out; /* daa result */
|
| 113 |
|
|
wire [7:0] ff_reg_in; /* register input */
|
| 114 |
|
|
wire [7:0] aa_reg_out, ff_reg_out; /* register outputs */
|
| 115 |
|
|
wire [7:0] new_flags; /* new flag byte */
|
| 116 |
|
|
wire [7:0] rst_addr; /* restart address */
|
| 117 |
|
|
wire [7:0] shft_out; /* shift result */
|
| 118 |
|
|
wire [15:8] bsign_ext; /* address alu b sign extend */
|
| 119 |
|
|
wire [15:0] adda_in, addb_in; /* address alu inputs */
|
| 120 |
|
|
wire [15:0] adder_out; /* math result */
|
| 121 |
|
|
wire [15:0] addr_alu, addr_hl, addr_pc, addr_sp; /* address mux terms */
|
| 122 |
|
|
wire [15:0] addr_reg_in; /* address register input */
|
| 123 |
|
|
wire [15:0] alua_in, alub_in; /* alu inputs */
|
| 124 |
|
|
wire [15:0] data_bus; /* alu output */
|
| 125 |
|
|
wire [15:0] de_reg_in; /* register inputs */
|
| 126 |
|
|
wire [15:0] af_reg_out, bc_reg_out; /* register outputs */
|
| 127 |
|
|
wire [15:0] de_reg_out, hl_reg_out;
|
| 128 |
|
|
wire [15:0] logic_out; /* logic result */
|
| 129 |
|
|
|
| 130 |
|
|
reg alt_af_reg, alt_bnk_reg; /* main/alt select */
|
| 131 |
|
|
reg alu_ovflo; /* final ov */
|
| 132 |
|
|
reg daa_sel, daa_op; /* daa operation */
|
| 133 |
|
|
reg decr_sel, decr_op; /* decrement operation */
|
| 134 |
|
|
reg dmar_reg; /* latched dma request */
|
| 135 |
|
|
reg ex_dehl_reg; /* special exchange */
|
| 136 |
|
|
reg ief1_reg; /* int enable flag 1 */
|
| 137 |
|
|
reg ief2_reg; /* int enable flag 2 */
|
| 138 |
|
|
reg imd1_reg; /* int mode 1 */
|
| 139 |
|
|
reg imd2_reg; /* int mode 2 */
|
| 140 |
|
|
reg intr_reg; /* latched int req */
|
| 141 |
|
|
reg ld_dmar, ld_intr; /* sample int/dma */
|
| 142 |
|
|
reg ld_pc; /* load pc */
|
| 143 |
|
|
reg nmi_hld; /* nmi edge tracker */
|
| 144 |
|
|
reg nmi_reg; /* latched nmi req */
|
| 145 |
|
|
reg tflg_nxt, tflg_reg; /* temp flag */
|
| 146 |
|
|
reg valid_dma; /* valid dma request */
|
| 147 |
|
|
reg valid_int, valid_nmi, valid_xhlt; /* valid int request */
|
| 148 |
|
|
reg word_sel, word_op; /* 16-bit operation */
|
| 149 |
|
|
reg xhlt_reg; /* halt exit */
|
| 150 |
|
|
reg [3:0] page_reg /* synthesis syn_preserve=1 */;
|
| 151 |
|
|
reg [7:0] inst_reg; /* instruction register */
|
| 152 |
|
|
reg [7:0] m_aa_reg, m_ff_reg, m_bb_reg, m_cc_reg; /* individual registers */
|
| 153 |
|
|
reg [7:0] m_dd_reg, m_ee_reg, m_hh_reg, m_ll_reg;
|
| 154 |
|
|
reg [7:0] a_aa_reg, a_ff_reg, a_bb_reg, a_cc_reg;
|
| 155 |
|
|
reg [7:0] a_dd_reg, a_ee_reg, a_hh_reg, a_ll_reg;
|
| 156 |
|
|
reg [7:0] ii_reg, rr_reg;
|
| 157 |
|
|
reg [7:0] din0_reg, din1_reg; /* data input registers */
|
| 158 |
|
|
reg [7:0] dout_io_reg, dout_mem_reg; /* data output registers */
|
| 159 |
|
|
reg [15:0] adda_out; /* address alu out */
|
| 160 |
|
|
reg [15:0] int_addr; /* interrupt address */
|
| 161 |
|
|
reg [15:0] ix_reg, iy_reg; /* index registers */
|
| 162 |
|
|
reg [15:0] pc_reg; /* program counter */
|
| 163 |
|
|
reg [15:0] sp_reg; /* stack pointer */
|
| 164 |
|
|
reg [15:0] tmp_reg; /* temporary register */
|
| 165 |
|
|
reg [`ADCTL_IDX:0] addsel_reg /* synthesis syn_preserve=1 */;
|
| 166 |
|
|
reg [`ALUA_IDX:0] alua_reg /* synthesis syn_preserve=1 */;
|
| 167 |
|
|
reg [`ALUB_IDX:0] alub_reg /* synthesis syn_preserve=1 */;
|
| 168 |
|
|
reg [`ALUOP_IDX:0] aluop_reg /* synthesis syn_preserve=1 */;
|
| 169 |
|
|
|
| 170 |
|
|
/*****************************************************************************************/
|
| 171 |
|
|
/* */
|
| 172 |
|
|
/* input synchronization */
|
| 173 |
|
|
/* */
|
| 174 |
|
|
/*****************************************************************************************/
|
| 175 |
|
|
always @ (posedge clkc or negedge resetb) begin
|
| 176 |
|
|
if (!resetb) begin
|
| 177 |
|
|
nmi_hld <= 1'b0;
|
| 178 |
|
|
valid_dma <= 1'b0;
|
| 179 |
|
|
valid_int <= 1'b0;
|
| 180 |
|
|
valid_nmi <= 1'b0;
|
| 181 |
|
|
valid_xhlt <= 1'b0;
|
| 182 |
|
|
end
|
| 183 |
|
|
else begin
|
| 184 |
|
|
nmi_hld <= (nmi_req && !valid_nmi) || (!(ivec_rd && nmi_reg) && nmi_hld);
|
| 185 |
|
|
valid_dma <= dma_req;
|
| 186 |
|
|
valid_int <= nmi_req || nmi_hld || ((&ief_ctl[1:0] || ief1_reg) && int_req);
|
| 187 |
|
|
valid_nmi <= nmi_req || nmi_hld;
|
| 188 |
|
|
valid_xhlt <= !dma_req && (nmi_req || nmi_hld || (ief1_reg && int_req));
|
| 189 |
|
|
end
|
| 190 |
|
|
end
|
| 191 |
|
|
|
| 192 |
|
|
/*****************************************************************************************/
|
| 193 |
|
|
/* */
|
| 194 |
|
|
/* interrupt mode and enables */
|
| 195 |
|
|
/* */
|
| 196 |
|
|
/*****************************************************************************************/
|
| 197 |
|
|
always @ (posedge clkc or negedge resetb) begin
|
| 198 |
|
|
if (!resetb) begin
|
| 199 |
|
|
ief1_reg <= 1'b0;
|
| 200 |
|
|
ief2_reg <= 1'b0;
|
| 201 |
|
|
imd1_reg <= 1'b0;
|
| 202 |
|
|
imd2_reg <= 1'b0;
|
| 203 |
|
|
end
|
| 204 |
|
|
else begin
|
| 205 |
|
|
if (|ief_ctl[2:1]) ief1_reg <= (ief_ctl[1]) ? ief_ctl[0] : (ief_ctl[0] && ief2_reg);
|
| 206 |
|
|
if (|ief_ctl[2:1]) ief2_reg <= (ief_ctl[1]) ? ief_ctl[0] :
|
| 207 |
|
|
(ief_ctl[0]) ? ief2_reg : (nmi_reg && ief1_reg);
|
| 208 |
|
|
if (|imd_ctl) imd1_reg <= imd_ctl[1] && !imd_ctl[0];
|
| 209 |
|
|
if (|imd_ctl) imd2_reg <= &imd_ctl;
|
| 210 |
|
|
end
|
| 211 |
|
|
end
|
| 212 |
|
|
|
| 213 |
|
|
assign vector_int = imd2_reg && !nmi_reg;
|
| 214 |
|
|
|
| 215 |
|
|
/*****************************************************************************************/
|
| 216 |
|
|
/* */
|
| 217 |
|
|
/* interrupt pending */
|
| 218 |
|
|
/* */
|
| 219 |
|
|
/*****************************************************************************************/
|
| 220 |
|
|
always @ (pc_sel or wait_st) begin
|
| 221 |
|
|
case (pc_sel)
|
| 222 |
|
|
`PC_DMA, /* dma xfer dma sample */
|
| 223 |
|
|
`PC_INT: ld_dmar = 1'b1; /* block inst dma sample */
|
| 224 |
|
|
`PC_NILD: ld_dmar = !wait_st; /* inst end dma sample */
|
| 225 |
|
|
default: ld_dmar = 1'b0;
|
| 226 |
|
|
endcase
|
| 227 |
|
|
end
|
| 228 |
|
|
|
| 229 |
|
|
always @ (pc_sel or wait_st) begin
|
| 230 |
|
|
case (pc_sel)
|
| 231 |
|
|
`PC_INT: ld_intr = 1'b1; /* block inst int sample */
|
| 232 |
|
|
`PC_NILD: ld_intr = !wait_st; /* inst end int sample */
|
| 233 |
|
|
default: ld_intr = 1'b0;
|
| 234 |
|
|
endcase
|
| 235 |
|
|
end
|
| 236 |
|
|
|
| 237 |
|
|
always @ (posedge clkc or negedge resetb) begin
|
| 238 |
|
|
if (!resetb) begin
|
| 239 |
|
|
dmar_reg <= 1'b0;
|
| 240 |
|
|
intr_reg <= 1'b0;
|
| 241 |
|
|
nmi_reg <= 1'b0;
|
| 242 |
|
|
xhlt_reg <= 1'b0;
|
| 243 |
|
|
end
|
| 244 |
|
|
else begin
|
| 245 |
|
|
if (ld_dmar) dmar_reg <= valid_dma;
|
| 246 |
|
|
if (ld_intr) intr_reg <= !valid_dma && (valid_nmi || (ief1_reg && valid_int));
|
| 247 |
|
|
if (ld_intr) nmi_reg <= !valid_dma && valid_nmi;
|
| 248 |
|
|
if (ld_intr) xhlt_reg <= !valid_dma && valid_xhlt;
|
| 249 |
|
|
end
|
| 250 |
|
|
end
|
| 251 |
|
|
|
| 252 |
|
|
/*****************************************************************************************/
|
| 253 |
|
|
/* */
|
| 254 |
|
|
/* register control */
|
| 255 |
|
|
/* */
|
| 256 |
|
|
/*****************************************************************************************/
|
| 257 |
|
|
always @ (pc_sel or dmar_reg or intr_reg or valid_dma or valid_int or wait_st) begin
|
| 258 |
|
|
case (pc_sel)
|
| 259 |
|
|
`PC_LD: ld_pc = !wait_st; /* load PC unconditionally */
|
| 260 |
|
|
`PC_NILD: ld_pc = !((ief1_reg && valid_int) || valid_nmi || valid_dma) && !wait_st;
|
| 261 |
|
|
`PC_NILD2: ld_pc = !(intr_reg || dmar_reg) && !wait_st; /* if no latched int */
|
| 262 |
|
|
default: ld_pc = 1'b0;
|
| 263 |
|
|
endcase
|
| 264 |
|
|
end
|
| 265 |
|
|
|
| 266 |
|
|
always @ (posedge clkc or negedge resetb) begin
|
| 267 |
|
|
if (!resetb) begin
|
| 268 |
|
|
alt_af_reg <= 1'b0;
|
| 269 |
|
|
alt_bnk_reg <= 1'b0;
|
| 270 |
|
|
ex_dehl_reg <= 1'b0;
|
| 271 |
|
|
end
|
| 272 |
|
|
else begin
|
| 273 |
|
|
alt_af_reg <= ex_af_pls ^ alt_af_reg;
|
| 274 |
|
|
alt_bnk_reg <= ex_bank_pls ^ alt_bnk_reg;
|
| 275 |
|
|
ex_dehl_reg <= ex_dehl_inst && ld_ctrl;
|
| 276 |
|
|
end
|
| 277 |
|
|
end
|
| 278 |
|
|
|
| 279 |
|
|
assign ld_flag = (sflg_en || zflg_en || |hflg_ctl || |pflg_ctl || |nflg_ctl ||
|
| 280 |
|
|
cflg_en) && !wait_st;
|
| 281 |
|
|
assign ld_regf = wr_addr[`WR_REG] && !wait_st;
|
| 282 |
|
|
|
| 283 |
|
|
/*****************************************************************************************/
|
| 284 |
|
|
/* */
|
| 285 |
|
|
/* cpu register interface */
|
| 286 |
|
|
/* */
|
| 287 |
|
|
/*****************************************************************************************/
|
| 288 |
|
|
assign ff_reg_in = (ld_flag) ? new_flags : data_bus[7:0];
|
| 289 |
|
|
assign de_reg_in = (ex_dehl_reg) ? hl_reg_out : data_bus;
|
| 290 |
|
|
|
| 291 |
|
|
assign ld_m_aa = ld_regf && wr_addr[`WR_AA] && !alt_af_reg;
|
| 292 |
|
|
assign ld_m_ff = ((ld_regf && wr_addr[`WR_FF]) || ld_flag) && !alt_af_reg;
|
| 293 |
|
|
assign ld_m_bb = ld_regf && wr_addr[`WR_BB] && !alt_bnk_reg;
|
| 294 |
|
|
assign ld_m_cc = ld_regf && wr_addr[`WR_CC] && !alt_bnk_reg;
|
| 295 |
|
|
assign ld_m_dd = ld_regf && wr_addr[`WR_DD] && !alt_bnk_reg;
|
| 296 |
|
|
assign ld_m_ee = ld_regf && wr_addr[`WR_EE] && !alt_bnk_reg;
|
| 297 |
|
|
assign ld_m_hh = ld_regf && wr_addr[`WR_HH] && !alt_bnk_reg;
|
| 298 |
|
|
assign ld_m_ll = ld_regf && wr_addr[`WR_LL] && !alt_bnk_reg;
|
| 299 |
|
|
assign ld_a_aa = ld_regf && wr_addr[`WR_AA] && alt_af_reg;
|
| 300 |
|
|
assign ld_a_ff = ((ld_regf && wr_addr[`WR_FF]) || ld_flag) && alt_af_reg;
|
| 301 |
|
|
assign ld_a_bb = ld_regf && wr_addr[`WR_BB] && alt_bnk_reg;
|
| 302 |
|
|
assign ld_a_cc = ld_regf && wr_addr[`WR_CC] && alt_bnk_reg;
|
| 303 |
|
|
assign ld_a_dd = ld_regf && wr_addr[`WR_DD] && alt_bnk_reg;
|
| 304 |
|
|
assign ld_a_ee = ld_regf && wr_addr[`WR_EE] && alt_bnk_reg;
|
| 305 |
|
|
assign ld_a_hh = ld_regf && wr_addr[`WR_HH] && alt_bnk_reg;
|
| 306 |
|
|
assign ld_a_ll = ld_regf && wr_addr[`WR_LL] && alt_bnk_reg;
|
| 307 |
|
|
assign ld_sp = ld_regf && wr_addr[`WR_SP];
|
| 308 |
|
|
assign ld_ix = ld_regf && wr_addr[`WR_IX];
|
| 309 |
|
|
assign ld_iy = ld_regf && wr_addr[`WR_IY];
|
| 310 |
|
|
assign ld_ii = ld_regf && wr_addr[`WR_II];
|
| 311 |
|
|
assign ld_rr = ld_regf && wr_addr[`WR_RR];
|
| 312 |
|
|
assign ld_tmp = ld_regf && wr_addr[`WR_TMP];
|
| 313 |
|
|
|
| 314 |
|
|
assign af_reg_out = (alt_af_reg) ? {a_aa_reg, a_ff_reg} : {m_aa_reg, m_ff_reg};
|
| 315 |
|
|
assign bc_reg_out = (alt_bnk_reg) ? {a_bb_reg, a_cc_reg} : {m_bb_reg, m_cc_reg};
|
| 316 |
|
|
assign de_reg_out = (alt_bnk_reg) ? {a_dd_reg, a_ee_reg} : {m_dd_reg, m_ee_reg};
|
| 317 |
|
|
assign hl_reg_out = (alt_bnk_reg) ? {a_hh_reg, a_ll_reg} : {m_hh_reg, m_ll_reg};
|
| 318 |
|
|
assign aa_reg_out = af_reg_out[15:8];
|
| 319 |
|
|
assign ff_reg_out = af_reg_out[7:0];
|
| 320 |
|
|
assign carry_bit = af_reg_out[0];
|
| 321 |
|
|
assign par_bit = af_reg_out[2];
|
| 322 |
|
|
assign sign_bit = af_reg_out[7];
|
| 323 |
|
|
assign zero_bit = af_reg_out[6];
|
| 324 |
|
|
assign hi_byte = (wr_addr[`WR_AA] && !wr_addr[`WR_FF]) ||
|
| 325 |
|
|
(wr_addr[`WR_BB] && !wr_addr[`WR_CC]) ||
|
| 326 |
|
|
(wr_addr[`WR_DD] && !wr_addr[`WR_EE]) ||
|
| 327 |
|
|
(wr_addr[`WR_HH] && !wr_addr[`WR_LL]) ||
|
| 328 |
|
|
wr_addr[`WR_II] || wr_addr[`WR_RR];
|
| 329 |
|
|
|
| 330 |
|
|
/*****************************************************************************************/
|
| 331 |
|
|
/* */
|
| 332 |
|
|
/* cpu registers */
|
| 333 |
|
|
/* */
|
| 334 |
|
|
/*****************************************************************************************/
|
| 335 |
|
|
always @ (posedge clkc or negedge clearb) begin
|
| 336 |
|
|
if (!clearb) begin
|
| 337 |
|
|
m_aa_reg <= 8'h00;
|
| 338 |
|
|
m_ff_reg <= 8'h00;
|
| 339 |
|
|
m_bb_reg <= 8'h00;
|
| 340 |
|
|
m_cc_reg <= 8'h00;
|
| 341 |
|
|
m_dd_reg <= 8'h00;
|
| 342 |
|
|
m_ee_reg <= 8'h00;
|
| 343 |
|
|
m_hh_reg <= 8'h00;
|
| 344 |
|
|
m_ll_reg <= 8'h00;
|
| 345 |
|
|
a_aa_reg <= 8'h00;
|
| 346 |
|
|
a_ff_reg <= 8'h00;
|
| 347 |
|
|
a_bb_reg <= 8'h00;
|
| 348 |
|
|
a_cc_reg <= 8'h00;
|
| 349 |
|
|
a_dd_reg <= 8'h00;
|
| 350 |
|
|
a_ee_reg <= 8'h00;
|
| 351 |
|
|
a_hh_reg <= 8'h00;
|
| 352 |
|
|
a_ll_reg <= 8'h00;
|
| 353 |
|
|
ix_reg <= 16'h0000;
|
| 354 |
|
|
iy_reg <= 16'h0000;
|
| 355 |
|
|
end
|
| 356 |
|
|
else begin
|
| 357 |
|
|
if (ld_m_aa) m_aa_reg <= data_bus[15:8];
|
| 358 |
|
|
if (ld_m_ff) m_ff_reg <= ff_reg_in;
|
| 359 |
|
|
if (ld_m_bb) m_bb_reg <= data_bus[15:8];
|
| 360 |
|
|
if (ld_m_cc) m_cc_reg <= data_bus[7:0];
|
| 361 |
|
|
if (ld_m_dd) m_dd_reg <= de_reg_in[15:8];
|
| 362 |
|
|
if (ld_m_ee) m_ee_reg <= de_reg_in[7:0];
|
| 363 |
|
|
if (ld_m_hh) m_hh_reg <= data_bus[15:8];
|
| 364 |
|
|
if (ld_m_ll) m_ll_reg <= data_bus[7:0];
|
| 365 |
|
|
if (ld_a_aa) a_aa_reg <= data_bus[15:8];
|
| 366 |
|
|
if (ld_a_ff) a_ff_reg <= ff_reg_in;
|
| 367 |
|
|
if (ld_a_bb) a_bb_reg <= data_bus[15:8];
|
| 368 |
|
|
if (ld_a_cc) a_cc_reg <= data_bus[7:0];
|
| 369 |
|
|
if (ld_a_dd) a_dd_reg <= de_reg_in[15:8];
|
| 370 |
|
|
if (ld_a_ee) a_ee_reg <= de_reg_in[7:0];
|
| 371 |
|
|
if (ld_a_hh) a_hh_reg <= data_bus[15:8];
|
| 372 |
|
|
if (ld_a_ll) a_ll_reg <= data_bus[7:0];
|
| 373 |
|
|
if (ld_ix) ix_reg <= data_bus;
|
| 374 |
|
|
if (ld_iy) iy_reg <= data_bus;
|
| 375 |
|
|
end
|
| 376 |
|
|
end
|
| 377 |
|
|
|
| 378 |
|
|
always @ (posedge clkc or negedge resetb) begin
|
| 379 |
|
|
if (!resetb) begin
|
| 380 |
|
|
ii_reg <= 8'h00;
|
| 381 |
|
|
pc_reg <= 16'h0000;
|
| 382 |
|
|
rr_reg <= 8'h00;
|
| 383 |
|
|
sp_reg <= 16'h0000;
|
| 384 |
|
|
tmp_reg <= 16'h0000;
|
| 385 |
|
|
end
|
| 386 |
|
|
else begin
|
| 387 |
|
|
if (ld_ii) ii_reg <= data_bus[15:8];
|
| 388 |
|
|
if (ld_pc) pc_reg <= data_bus;
|
| 389 |
|
|
if (ld_rr) rr_reg <= data_bus[15:8];
|
| 390 |
|
|
if (ld_sp) sp_reg <= data_bus;
|
| 391 |
|
|
if (ld_tmp) tmp_reg <= (ivec_rd) ? {ii_reg, data_in} : data_bus;
|
| 392 |
|
|
end
|
| 393 |
|
|
end
|
| 394 |
|
|
|
| 395 |
|
|
/*****************************************************************************************/
|
| 396 |
|
|
/* */
|
| 397 |
|
|
/* temporary flag */
|
| 398 |
|
|
/* */
|
| 399 |
|
|
/*****************************************************************************************/
|
| 400 |
|
|
assign ld_tflg = |tflg_ctl && !wait_st;
|
| 401 |
|
|
|
| 402 |
|
|
always @ (tflg_ctl or alu_one or alu_zero or ff_reg_out) begin
|
| 403 |
|
|
casex (tflg_ctl)
|
| 404 |
|
|
`TFLG_1: tflg_nxt = alu_one; /* blk set if done (next xfr) */
|
| 405 |
|
|
`TFLG_Z: tflg_nxt = alu_zero; /* blk set if done (this xfr) */
|
| 406 |
|
|
`TFLG_B: tflg_nxt = alu_zero || !ff_reg_out[2]; /* blk cp set if done or match */
|
| 407 |
|
|
default: tflg_nxt = 1'b0;
|
| 408 |
|
|
endcase
|
| 409 |
|
|
end
|
| 410 |
|
|
|
| 411 |
|
|
always @ (posedge clkc or negedge resetb) begin
|
| 412 |
|
|
if (!resetb) tflg_reg <= 1'b0;
|
| 413 |
|
|
else if (ld_tflg) tflg_reg <= tflg_nxt;
|
| 414 |
|
|
end
|
| 415 |
|
|
|
| 416 |
|
|
/*****************************************************************************************/
|
| 417 |
|
|
/* */
|
| 418 |
|
|
/* data input and data output registers */
|
| 419 |
|
|
/* */
|
| 420 |
|
|
/*****************************************************************************************/
|
| 421 |
|
|
assign ld_dout_io = do_ctl[1] && !wait_st;
|
| 422 |
|
|
assign ld_dout_mem = do_ctl[2] && !wait_st;
|
| 423 |
|
|
|
| 424 |
|
|
always @ (posedge clkc or negedge resetb) begin
|
| 425 |
|
|
if (!resetb) begin
|
| 426 |
|
|
din0_reg <= 8'h00;
|
| 427 |
|
|
din1_reg <= 8'h00;
|
| 428 |
|
|
dout_io_reg <= 8'h00;
|
| 429 |
|
|
dout_mem_reg <= 8'h00;
|
| 430 |
|
|
end
|
| 431 |
|
|
else begin
|
| 432 |
|
|
if (di_ctl[0]) din0_reg <= data_in;
|
| 433 |
|
|
if (di_ctl[1]) din1_reg <= data_in;
|
| 434 |
|
|
if (ld_dout_io) dout_io_reg <= data_bus[7:0];
|
| 435 |
|
|
if (ld_dout_mem) dout_mem_reg <= (do_ctl[0]) ? data_bus[15:8] : data_bus[7:0];
|
| 436 |
|
|
end
|
| 437 |
|
|
end
|
| 438 |
|
|
|
| 439 |
|
|
/*****************************************************************************************/
|
| 440 |
|
|
/* */
|
| 441 |
|
|
/* instruction and page registers */
|
| 442 |
|
|
/* */
|
| 443 |
|
|
/*****************************************************************************************/
|
| 444 |
|
|
always @ (posedge clkc or negedge resetb) begin
|
| 445 |
|
|
if (!resetb) inst_reg <= 8'h00;
|
| 446 |
|
|
else if (ld_inst) inst_reg <= data_in;
|
| 447 |
|
|
end
|
| 448 |
|
|
|
| 449 |
|
|
always @ (posedge clkc or negedge resetb) begin
|
| 450 |
|
|
if (!resetb) page_reg <= 4'b0000;
|
| 451 |
|
|
else if (ld_page && ld_ctrl) page_reg <= page_sel;
|
| 452 |
|
|
end
|
| 453 |
|
|
|
| 454 |
|
|
/*****************************************************************************************/
|
| 455 |
|
|
/* */
|
| 456 |
|
|
/* alu control pipeline registers */
|
| 457 |
|
|
/* */
|
| 458 |
|
|
/*****************************************************************************************/
|
| 459 |
|
|
always @ (aluop_sel) begin
|
| 460 |
|
|
case (aluop_sel) //synopsys parallel_case
|
| 461 |
|
|
`ALUOP_DAA: daa_sel = 1'b1;
|
| 462 |
|
|
default: daa_sel = 1'b0;
|
| 463 |
|
|
endcase
|
| 464 |
|
|
end
|
| 465 |
|
|
|
| 466 |
|
|
always @ (aluop_sel) begin
|
| 467 |
|
|
case (aluop_sel) //synopsys parallel_case
|
| 468 |
|
|
`ALUOP_BDEC: decr_sel = 1'b1;
|
| 469 |
|
|
default: decr_sel = 1'b0;
|
| 470 |
|
|
endcase
|
| 471 |
|
|
end
|
| 472 |
|
|
|
| 473 |
|
|
always @ (aluop_sel) begin
|
| 474 |
|
|
case (aluop_sel) //synopsys parallel_case
|
| 475 |
|
|
`ALUOP_ADC,
|
| 476 |
|
|
`ALUOP_ADD,
|
| 477 |
|
|
`ALUOP_PASS,
|
| 478 |
|
|
`ALUOP_SBC,
|
| 479 |
|
|
`ALUOP_SUB: word_sel = 1'b1;
|
| 480 |
|
|
default: word_sel = 1'b0;
|
| 481 |
|
|
endcase
|
| 482 |
|
|
end
|
| 483 |
|
|
|
| 484 |
|
|
always @ (posedge clkc or negedge resetb) begin
|
| 485 |
|
|
if (!resetb) begin
|
| 486 |
|
|
addsel_reg <= `ADD_RSTVAL;
|
| 487 |
|
|
alua_reg <= `ALUA_RSTVAL;
|
| 488 |
|
|
alub_reg <= `ALUB_RSTVAL;
|
| 489 |
|
|
aluop_reg <= `ALUOP_RSTVAL;
|
| 490 |
|
|
daa_op <= 1'b0;
|
| 491 |
|
|
decr_op <= 1'b0;
|
| 492 |
|
|
word_op <= 1'b0;
|
| 493 |
|
|
end
|
| 494 |
|
|
else if (ld_ctrl) begin
|
| 495 |
|
|
addsel_reg <= add_sel;
|
| 496 |
|
|
alua_reg <= alua_sel;
|
| 497 |
|
|
alub_reg <= alub_sel;
|
| 498 |
|
|
aluop_reg <= aluop_sel;
|
| 499 |
|
|
daa_op <= daa_sel;
|
| 500 |
|
|
decr_op <= decr_sel;
|
| 501 |
|
|
word_op <= word_sel;
|
| 502 |
|
|
end
|
| 503 |
|
|
end
|
| 504 |
|
|
|
| 505 |
|
|
/*****************************************************************************************/
|
| 506 |
|
|
/* */
|
| 507 |
|
|
/* bit manipulation constant generator */
|
| 508 |
|
|
/* */
|
| 509 |
|
|
/*****************************************************************************************/
|
| 510 |
|
|
assign bit7 = (inst_reg[7] && !inst_reg[6]) ^ (inst_reg[5:3] == 3'b111);
|
| 511 |
|
|
assign bit6 = (inst_reg[7] && !inst_reg[6]) ^ (inst_reg[5:3] == 3'b110);
|
| 512 |
|
|
assign bit5 = (inst_reg[7] && !inst_reg[6]) ^ (inst_reg[5:3] == 3'b101);
|
| 513 |
|
|
assign bit4 = (inst_reg[7] && !inst_reg[6]) ^ (inst_reg[5:3] == 3'b100);
|
| 514 |
|
|
assign bit3 = (inst_reg[7] && !inst_reg[6]) ^ (inst_reg[5:3] == 3'b011);
|
| 515 |
|
|
assign bit2 = (inst_reg[7] && !inst_reg[6]) ^ (inst_reg[5:3] == 3'b010);
|
| 516 |
|
|
assign bit1 = (inst_reg[7] && !inst_reg[6]) ^ (inst_reg[5:3] == 3'b001);
|
| 517 |
|
|
assign bit0 = (inst_reg[7] && !inst_reg[6]) ^ (inst_reg[5:3] == 3'b000);
|
| 518 |
|
|
assign bit_mask = {bit7, bit6, bit5, bit4, bit3, bit2, bit1, bit0};
|
| 519 |
|
|
|
| 520 |
|
|
/*****************************************************************************************/
|
| 521 |
|
|
/* */
|
| 522 |
|
|
/* decimal adjust accumulator constant generator */
|
| 523 |
|
|
/* */
|
| 524 |
|
|
/*****************************************************************************************/
|
| 525 |
|
|
assign daa_l1 = !ff_reg_out[1] && !ff_reg_out[4] &&
|
| 526 |
|
|
(!aa_reg_out[3] || (aa_reg_out[3] && !aa_reg_out[2] && !aa_reg_out[1]));
|
| 527 |
|
|
assign daa_l2 = !ff_reg_out[1] && !ff_reg_out[4] &&
|
| 528 |
|
|
(aa_reg_out[3] && (aa_reg_out[2] || aa_reg_out[1]));
|
| 529 |
|
|
assign daa_l3 = !ff_reg_out[1] && ff_reg_out[4] && (!aa_reg_out[3] && !aa_reg_out[2]);
|
| 530 |
|
|
assign daa_l4 = ff_reg_out[1] && !ff_reg_out[4] &&
|
| 531 |
|
|
(!aa_reg_out[3] || (aa_reg_out[3] && !aa_reg_out[2] && !aa_reg_out[1]));
|
| 532 |
|
|
assign daa_l5 = ff_reg_out[1] && ff_reg_out[4] &&
|
| 533 |
|
|
((!aa_reg_out[3] && aa_reg_out[2] && aa_reg_out[1]) || aa_reg_out[3]);
|
| 534 |
|
|
assign daa_h1 = !ff_reg_out[0] && (aa_reg_out[7] && (aa_reg_out[6] || aa_reg_out[5]));
|
| 535 |
|
|
assign daa_h2 = ff_reg_out[0] &&
|
| 536 |
|
|
(!aa_reg_out[7] && !aa_reg_out[6] && (!aa_reg_out[5] || !aa_reg_out[4]));
|
| 537 |
|
|
assign daa_h3 = !ff_reg_out[0] &&
|
| 538 |
|
|
(aa_reg_out[7] && (aa_reg_out[6] || aa_reg_out[5] || aa_reg_out[4]));
|
| 539 |
|
|
assign daa_h4 = ff_reg_out[0] && (!aa_reg_out[7] && !aa_reg_out[6]);
|
| 540 |
|
|
assign daa_h5 = ff_reg_out[0] &&
|
| 541 |
|
|
((aa_reg_out[6] && aa_reg_out[5] && aa_reg_out[4]) || aa_reg_out[7]);
|
| 542 |
|
|
assign daa_h6 = !ff_reg_out[0] &&
|
| 543 |
|
|
((!aa_reg_out[6] && !aa_reg_out[5] && !aa_reg_out[4]) || !aa_reg_out[7]);
|
| 544 |
|
|
assign daa_h7 = ff_reg_out[0] && ((aa_reg_out[6] && aa_reg_out[5]) || aa_reg_out[7]);
|
| 545 |
|
|
|
| 546 |
|
|
assign daa1 = daa_l2 || daa_l3 || daa_l5;
|
| 547 |
|
|
assign daa2 = daa_l2 || daa_l3;
|
| 548 |
|
|
assign daa3 = daa_l5;
|
| 549 |
|
|
assign daa4 = daa_l5 && (daa_h6 || daa_h7);
|
| 550 |
|
|
assign daa5 = (daa_l1 && (daa_h1 || daa_h2)) || (daa_l2 && (daa_h2 || daa_h3)) ||
|
| 551 |
|
|
(daa_l3 && (daa_h1 || daa_h4)) || (daa_l4 && daa_h5) ||
|
| 552 |
|
|
(daa_l5 && daa_h6);
|
| 553 |
|
|
assign daa6 = (daa_l1 && (daa_h1 || daa_h2)) || (daa_l2 && (daa_h2 || daa_h3)) ||
|
| 554 |
|
|
(daa_l3 && (daa_h1 || daa_h4)) || (daa_l5 && daa_h6);
|
| 555 |
|
|
assign daa7 = (daa_l4 && daa_h5) || (daa_l5 && (daa_h6 || daa_h7));
|
| 556 |
|
|
|
| 557 |
|
|
assign daa_out = {daa7, daa6, daa5, daa4, daa3, daa2, daa1, 1'b0};
|
| 558 |
|
|
assign carry_daa = (daa_l1 && (daa_h1 || daa_h2)) || (daa_l2 && (daa_h2 || daa_h3)) ||
|
| 559 |
|
|
(daa_l3 && (daa_h1 || daa_h4)) || (daa_l4 && daa_h5) ||
|
| 560 |
|
|
(daa_l5 && daa_h7);
|
| 561 |
|
|
|
| 562 |
|
|
/*****************************************************************************************/
|
| 563 |
|
|
/* */
|
| 564 |
|
|
/* interrupt/restart address generator */
|
| 565 |
|
|
/* */
|
| 566 |
|
|
/*****************************************************************************************/
|
| 567 |
|
|
assign rst_addr = {2'b00, inst_reg[5:3], 3'b000};
|
| 568 |
|
|
|
| 569 |
|
|
always @ (nmi_reg or imd2_reg or imd1_reg or din0_reg or din1_reg) begin
|
| 570 |
|
|
casex ({nmi_reg, imd2_reg, imd1_reg})
|
| 571 |
|
|
3'b001: int_addr = 16'h0038;
|
| 572 |
|
|
3'b010: int_addr = {din1_reg, din0_reg};
|
| 573 |
|
|
3'b1xx: int_addr = 16'h0066;
|
| 574 |
|
|
default: int_addr = 16'h0000;
|
| 575 |
|
|
endcase
|
| 576 |
|
|
end
|
| 577 |
|
|
|
| 578 |
|
|
/*****************************************************************************************/
|
| 579 |
|
|
/* */
|
| 580 |
|
|
/* alu input selects */
|
| 581 |
|
|
/* */
|
| 582 |
|
|
/*****************************************************************************************/
|
| 583 |
|
|
aluamux AMUX ( .adda_in(adda_in), .alua_in(alua_in), .alua_reg(alua_reg),
|
| 584 |
|
|
.aa_reg_out(aa_reg_out), .bit_mask(bit_mask), .daa_out(daa_out),
|
| 585 |
|
|
.hl_reg_out(hl_reg_out), .ii_reg(ii_reg), .int_addr(int_addr),
|
| 586 |
|
|
.ix_reg(ix_reg), .iy_reg(iy_reg), .pc_reg(pc_reg), .rr_reg(rr_reg),
|
| 587 |
|
|
.rst_addr(rst_addr) );
|
| 588 |
|
|
|
| 589 |
|
|
alubmux BMUX ( .addb_in(addb_in), .alub_in(alub_in), .alub_reg(alub_reg),
|
| 590 |
|
|
.af_reg_out(af_reg_out), .bc_reg_out(bc_reg_out), .de_reg_out(de_reg_out),
|
| 591 |
|
|
.din0_reg(din0_reg), .din1_reg(din1_reg), .hl_reg_out(hl_reg_out),
|
| 592 |
|
|
.ix_reg(ix_reg), .iy_reg(iy_reg), .pc_reg(pc_reg), .sp_reg(sp_reg),
|
| 593 |
|
|
.tmp_reg(tmp_reg) );
|
| 594 |
|
|
|
| 595 |
|
|
/*****************************************************************************************/
|
| 596 |
|
|
/* */
|
| 597 |
|
|
/* function units */
|
| 598 |
|
|
/* */
|
| 599 |
|
|
/*****************************************************************************************/
|
| 600 |
|
|
alu_log ALULOG ( .logic_c(logic_c), .logic_hc(logic_hc), .logic_out(logic_out),
|
| 601 |
|
|
.alua_in(alua_in), .alub_in(alub_in), .aluop_reg(aluop_reg[`AOP_IDX:0]),
|
| 602 |
|
|
.carry_bit(carry_bit) );
|
| 603 |
|
|
|
| 604 |
|
|
alu_math ALUMATH ( .adder_c(adder_c), .adder_hc(adder_hc), .adder_out(adder_out),
|
| 605 |
|
|
.adder_ov(adder_ov), .alua_in(alua_in), .alub_in(alub_in),
|
| 606 |
|
|
.aluop_reg(aluop_reg[`AOP_IDX:0]), .carry_bit(carry_bit),
|
| 607 |
|
|
.carry_daa(carry_daa), .daa_op(daa_op), .word_op(word_op) );
|
| 608 |
|
|
|
| 609 |
|
|
alu_shft ALUSHFT ( .shft_c(shft_c), .shft_out(shft_out), .alub_in(alub_in[7:0]),
|
| 610 |
|
|
.aluop_reg(aluop_reg[`AOP_IDX:0]), .carry_bit(carry_bit) );
|
| 611 |
|
|
|
| 612 |
|
|
aluout ALUOUT ( .cry_nxt(cry_nxt), .data_bus(data_bus), .hcar_nxt(hcar_nxt),
|
| 613 |
|
|
.one_nxt(one_nxt), .par_nxt(par_nxt), .sign_nxt(sign_nxt),
|
| 614 |
|
|
.zero_nxt(zero_nxt), .adder_c(adder_c), .adder_hc(adder_hc),
|
| 615 |
|
|
.adder_out(adder_out), .hi_byte(hi_byte), .logic_c(logic_c),
|
| 616 |
|
|
.logic_hc(logic_hc), .logic_out(logic_out), .shft_c(shft_c),
|
| 617 |
|
|
.shft_out(shft_out), .unit_sel(aluop_reg[7:6]), .word_op(word_op) );
|
| 618 |
|
|
|
| 619 |
|
|
/*****************************************************************************************/
|
| 620 |
|
|
/* */
|
| 621 |
|
|
/* flag generation */
|
| 622 |
|
|
/* */
|
| 623 |
|
|
/*****************************************************************************************/
|
| 624 |
|
|
assign alu_carry = decr_op ^ cry_nxt;
|
| 625 |
|
|
assign alu_hcar = (hflg_ctl[1]) ? hflg_ctl[0] : (decr_op ^ hcar_nxt);
|
| 626 |
|
|
assign alu_neg = (nflg_ctl[1]) ? nflg_ctl[0] : sign_nxt;
|
| 627 |
|
|
assign alu_one = one_nxt;
|
| 628 |
|
|
assign alu_sign = sign_nxt;
|
| 629 |
|
|
assign alu_zero = zero_nxt;
|
| 630 |
|
|
|
| 631 |
|
|
always @ (pflg_ctl or adder_ov or ief2_reg or par_nxt or zero_nxt) begin
|
| 632 |
|
|
case (pflg_ctl)
|
| 633 |
|
|
`PFLG_V: alu_ovflo = adder_ov;
|
| 634 |
|
|
`PFLG_1: alu_ovflo = 1'b1;
|
| 635 |
|
|
`PFLG_P: alu_ovflo = par_nxt;
|
| 636 |
|
|
`PFLG_B: alu_ovflo = !zero_nxt;
|
| 637 |
|
|
`PFLG_F: alu_ovflo = ief2_reg;
|
| 638 |
|
|
default: alu_ovflo = 1'b0;
|
| 639 |
|
|
endcase
|
| 640 |
|
|
end
|
| 641 |
|
|
|
| 642 |
|
|
assign new_flags[7] = (sflg_en) ? alu_sign : ff_reg_out[7];
|
| 643 |
|
|
assign new_flags[6] = (zflg_en) ? alu_zero : ff_reg_out[6];
|
| 644 |
|
|
assign new_flags[5] = ff_reg_out[5];
|
| 645 |
|
|
assign new_flags[4] = (|hflg_ctl) ? alu_hcar : ff_reg_out[4];
|
| 646 |
|
|
assign new_flags[3] = ff_reg_out[3];
|
| 647 |
|
|
assign new_flags[2] = (|pflg_ctl) ? alu_ovflo : ff_reg_out[2];
|
| 648 |
|
|
assign new_flags[1] = (|nflg_ctl) ? alu_neg : ff_reg_out[1];
|
| 649 |
|
|
assign new_flags[0] = (cflg_en) ? alu_carry : ff_reg_out[0];
|
| 650 |
|
|
|
| 651 |
|
|
/*****************************************************************************************/
|
| 652 |
|
|
/* */
|
| 653 |
|
|
/* address alu */
|
| 654 |
|
|
/* */
|
| 655 |
|
|
/*****************************************************************************************/
|
| 656 |
|
|
assign bsign_ext = {addb_in[7], addb_in[7], addb_in[7], addb_in[7],
|
| 657 |
|
|
addb_in[7], addb_in[7], addb_in[7], addb_in[7]};
|
| 658 |
|
|
|
| 659 |
|
|
always @ (aluop_reg or adda_in or addb_in or bsign_ext) begin
|
| 660 |
|
|
case (aluop_reg)
|
| 661 |
|
|
`ALUOP_ADS: adda_out = adda_in + {bsign_ext[15:8], addb_in[7:0]};
|
| 662 |
|
|
`ALUOP_ADD: adda_out = adda_in + addb_in;
|
| 663 |
|
|
`ALUOP_APAS: adda_out = adda_in;
|
| 664 |
|
|
default: adda_out = addb_in;
|
| 665 |
|
|
endcase
|
| 666 |
|
|
end
|
| 667 |
|
|
|
| 668 |
|
|
assign addr_alu = (addsel_reg[`AD_ALU]) ? adda_out : 16'h0000;
|
| 669 |
|
|
assign addr_hl = (addsel_reg[`AD_HL]) ? hl_reg_out : 16'h0000;
|
| 670 |
|
|
assign addr_pc = (addsel_reg[`AD_PC]) ? pc_reg : 16'h0000;
|
| 671 |
|
|
assign addr_sp = (addsel_reg[`AD_SP]) ? sp_reg : 16'h0000;
|
| 672 |
|
|
|
| 673 |
|
|
assign addr_reg_in = addr_alu | addr_hl | addr_pc | addr_sp;
|
| 674 |
|
|
|
| 675 |
|
|
endmodule
|
| 676 |
|
|
|
| 677 |
|
|
|
| 678 |
|
|
|
| 679 |
|
|
|
| 680 |
|
|
|
| 681 |
|
|
|
| 682 |
|
|
|
| 683 |
|
|
|
| 684 |
|
|
|
| 685 |
|
|
|
| 686 |
|
|
|
