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Implement call nn

This commit is contained in:
Koray Yanik 2021-02-22 23:07:10 +00:00
parent 7e558104de
commit f6e68231fd
4 changed files with 49 additions and 18 deletions
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23
rtl/cpu/control.sv
View File

@ -77,12 +77,14 @@ module control (
logic decoder_alu_op_valid;
logic decoder_memory_we;
adr_src_t decoder_adr_src;
logic decoder_sp_we;
logic is_undef;
logic pc_incr;
logic instr_valid;
logic branch_taken;
logic branch_cc_true;
logic branch_always;
sp_src_t sp_src;
pc_src_t pc_src;
@ -108,10 +110,15 @@ module control (
`DEF_FF(operand1_r, operand1_next, operand1_we, '0);
assign pc_we = (nreset_r & ~is_undef & ~halted_r) & (pc_incr | branch_taken);
assign pc_next = (branch_taken & pc_src == PC_SRC_OPERAND8) ? (pc_r + {{8{operand0_r[7]}}, operand0_r}) :
(pc_r + 16'b1);
assign pc_next = (branch_taken & pc_src == PC_SRC_OPERAND8) ? (pc_r + {{8{operand0_r[7]}}, operand0_r}) :
(branch_taken & pc_src == PC_SRC_OPERAND16) ? {operand1_r, operand0_r} :
(pc_r + 16'b1);
assign sp_next = (sp_src == SP_SRC_OPERAND16) ? {operand1_r, operand0_r} : '0;
assign sp_we = instr_valid & decoder_sp_we;
assign sp_next = (sp_src == SP_SRC_OPERAND16) ? {operand1_r, operand0_r} :
(sp_src == SP_SRC_INC) ? (sp_r + 16'h01) :
(sp_src == SP_SRC_DEC) ? (sp_r + 16'hFFFF) :
'0;
assign instr_we = (state_r == ST1_DEC);
assign instr_next = rdata_i;
@ -135,7 +142,8 @@ module control (
ST2_DEC: state_next = decoder_need_instr2 ? ST3_DEC : ST3_EXEC;
ST3_DEC: state_next = ST4_EXEC;
ST3_EXEC: state_next = ST0_ADDR;
ST4_EXEC: state_next = ST0_ADDR;
ST4_EXEC: state_next = decoder_is_multicycle ? ST5_EXEC : ST0_ADDR;
ST5_EXEC: state_next = ST0_ADDR;
endcase
end
@ -150,7 +158,7 @@ module control (
.is_multicycle_o(decoder_is_multicycle),
.undef_o (decoder_is_undef),
.sp_we_o (sp_we),
.sp_we_o (decoder_sp_we),
.sp_src_o (sp_src),
.alu_op_valid_o(decoder_alu_op_valid),
@ -168,6 +176,7 @@ module control (
.memory_we_o (decoder_memory_we),
.adr_src_o (decoder_adr_src),
.branch_always_o(branch_always),
.cc_o (cc),
.pc_src_o (pc_src)
);
@ -177,12 +186,12 @@ module control (
assign decoder_instr2_selected = (state_r == ST3_DEC) ? rdata_i : operand1_r;
assign is_undef = instr_valid & decoder_is_undef;
assign instr_valid = (state_r == ST2_EXEC | state_r == ST3_EXEC | state_r == ST4_EXEC);
assign instr_valid = (state_r == ST2_EXEC | state_r == ST3_EXEC | state_r == ST4_EXEC | state_r == ST5_EXEC);
assign alu_op_valid_o = decoder_alu_op_valid & instr_valid;
assign pc_incr = (state_r == ST0_ADDR) | (state_r == ST1_DEC & decoder_need_instr1) | (state_r == ST2_DEC & decoder_need_instr2);
assign branch_taken = instr_valid & (pc_src != PC_SRC_SEQ) & branch_cc_true;
assign branch_taken = instr_valid & (pc_src != PC_SRC_SEQ) & (branch_cc_true | branch_always);
assign branch_cc_true = ((cc == CC_NZ) & ~f_i[7]) |
((cc == CC_Z) & f_i[7]) |
((cc == CC_NC) & ~f_i[4]) |

3
rtl/cpu/cpu.sv
View File

@ -117,6 +117,8 @@ module cpu (
(op_src == OP_SRC_OPERAND8) ? operand8 :
(op_src == OP_SRC_REG8) ? reg8_rdata :
(op_src == OP_SRC_MEMORY) ? rdata_i :
(op_src == OP_SRC_PC_L) ? pc[7:0] :
(op_src == OP_SRC_PC_H) ? pc[15:8] :
'X;
assign reg8_we = instr_valid & (op_dest == OP_DEST_REG8);
@ -126,6 +128,7 @@ module cpu (
assign reg16_rselect2 = reg16_wselect;
assign address_o = (adr_src == ADR_SRC_HL) ? hl :
(adr_src == ADR_SRC_SP) ? sp :
(adr_src == ADR_SRC_REG8) ? {8'hFF, reg8_rdata} :
(adr_src == ADR_SRC_REG16) ? reg16_rdata :
(adr_src == ADR_SRC_OPERAND8) ? {8'hFF, operand8} :

15
rtl/cpu/cpu_pkg.svh
View File

@ -11,7 +11,8 @@ package cpu_pkg;
ST2_DEC,
ST3_DEC,
ST3_EXEC,
ST4_EXEC
ST4_EXEC,
ST5_EXEC
} state_t;
typedef enum logic [2:0] {
@ -66,7 +67,9 @@ package cpu_pkg;
OP_SRC_OPERAND8,
OP_SRC_MEMORY,
OP_SRC_OPERAND16,
OP_SRC_REG16
OP_SRC_REG16,
OP_SRC_PC_L,
OP_SRC_PC_H
} op_src_t;
typedef enum {
@ -77,12 +80,15 @@ package cpu_pkg;
} op_dest_t;
typedef enum {
SP_SRC_OPERAND16
SP_SRC_OPERAND16,
SP_SRC_INC,
SP_SRC_DEC
} sp_src_t;
typedef enum {
ADR_SRC_PC,
ADR_SRC_HL,
ADR_SRC_SP,
ADR_SRC_REG8, // extended with FF
ADR_SRC_REG16,
ADR_SRC_OPERAND8, // extended with FF
@ -91,7 +97,8 @@ package cpu_pkg;
typedef enum {
PC_SRC_SEQ,
PC_SRC_OPERAND8
PC_SRC_OPERAND8,
PC_SRC_OPERAND16
} pc_src_t;
endpackage

26
rtl/cpu/decode.sv
View File

@ -29,6 +29,7 @@ module decode (
output reg16_t reg16_dest_o,
output reg16_t reg16_src_o,
output logic branch_always_o,
output cc_t cc_o,
output pc_src_t pc_src_o,
@ -60,6 +61,7 @@ module decode (
logic is_inc_a;
logic is_inc_r;
logic is_jr_cc_n;
logic is_call_nn;
reg8_t reg8_dest;
reg8_t reg8_src;
@ -92,6 +94,7 @@ module decode (
assign is_inc_r = (dec_x == 2'h0) & (dec_z == 3'h4);
assign is_jr_cc_n = (dec_x == 2'h0) & (dec_z == 2'h0) & dec_y[2];
assign is_call_nn = (instr0_i == 8'hCD);
assign reg8_src = is_cb ? reg8_t'(instr1_i[2:0]) :
is_ldh_c_a ? REG8_C :
@ -99,14 +102,17 @@ module decode (
reg8_t'(dec_z);
assign reg8_dest = reg8_t'(dec_y);
assign need_instr1_o = is_ld_sp_nn | is_ld_rr_nn | is_ld_a_nn | is_cb | is_jr_cc_n | is_ld_r_n | is_ldh_n_a;
assign need_instr2_o = is_ld_sp_nn | is_ld_rr_nn | is_ld_a_nn;
assign is_multicycle_o = is_ld_a_rr;
assign need_instr1_o = is_ld_sp_nn | is_ld_rr_nn | is_ld_a_nn | is_call_nn | is_cb | is_jr_cc_n | is_ld_r_n | is_ldh_n_a;
assign need_instr2_o = is_ld_sp_nn | is_ld_rr_nn | is_ld_a_nn | is_call_nn;
assign is_multicycle_o = is_ld_a_rr | is_call_nn;
assign undef_o = ~(is_ldh_n_a | is_ld_r_r | is_ld_sp_nn | is_ld_rr_nn | is_alu_a_r | is_ldd_hl_a | is_bit_n_r |
is_jr_cc_n | is_ld_r_n | is_ldh_c_a | is_inc_r | is_ld_rr_a | is_ld_a_rr);
is_jr_cc_n | is_ld_r_n | is_ldh_c_a | is_inc_r | is_ld_rr_a | is_ld_a_rr | is_call_nn);
assign sp_we_o = is_ld_sp_nn & (state_i == ST4_EXEC);
assign sp_we_o = is_ld_sp_nn | is_call_nn;
assign sp_src_o = is_ld_sp_nn ? SP_SRC_OPERAND16 :
is_call_nn ? SP_SRC_DEC :
sp_src_t'('X);
assign alu_op_valid_o = is_alu_a_r | is_bit_n_r | is_ld_a_n | is_ld_a_rr | is_ld_a_nn | is_inc_r;
assign alu_op_o = is_bit_n_r ? ALU_OP_BIT :
@ -132,6 +138,7 @@ module decode (
is_ldd_hl_a ? OP_DEST_REG16 :
is_inc_a ? OP_DEST_A :
is_inc_r ? OP_DEST_REG8 :
is_call_nn ? OP_DEST_MEMORY :
op_dest_t'('X);
assign op_src_o = (is_ld_r_r & reg8_src == REG8_A) ? OP_SRC_A :
@ -147,6 +154,8 @@ module decode (
is_ld_rr_nn ? OP_SRC_OPERAND16 :
is_ldd_hl_a ? OP_SRC_REG16 :
is_bit_n_r ? OP_SRC_REG8 :
is_call_nn & (state_i == ST4_EXEC) ? OP_SRC_PC_L :
is_call_nn & (state_i == ST5_EXEC) ? OP_SRC_PC_H :
op_src_t'('X);
assign reg8_dest_o = reg8_dest;
@ -154,7 +163,8 @@ module decode (
assign reg16_src_o = is_ldd_hl_a ? REG16_HL : reg16_t'(dec_p);
assign reg16_dest_o = is_ldd_hl_a ? REG16_HL : reg16_t'(dec_p);
assign pc_src_o = is_jr_cc_n ? PC_SRC_OPERAND8 :
assign pc_src_o = is_jr_cc_n ? PC_SRC_OPERAND8 :
is_call_nn ? PC_SRC_OPERAND16 :
PC_SRC_SEQ;
assign adr_src_o = (is_ld_r_r & reg8_dest == REG8_PHL) ? ADR_SRC_HL :
@ -167,10 +177,12 @@ module decode (
is_ld_a_nn ? ADR_SRC_OPERAND16 :
is_ld_a_rr ? ADR_SRC_REG16 :
is_ld_rr_a ? ADR_SRC_REG16 :
is_call_nn ? ADR_SRC_SP :
ADR_SRC_PC;
assign branch_always_o = is_call_nn;
assign cc_o = cc_t'(dec_y[1:0]);
assign memory_we_o = is_ldd_hl_a | is_ldh_c_a | is_ldh_n_a | is_ld_rr_a | (is_ld_r_n & reg8_dest == REG8_PHL) | (is_ld_r_r & reg8_dest == REG8_PHL);
assign memory_we_o = is_ldd_hl_a | is_ldh_c_a | is_ldh_n_a | is_ld_rr_a | (is_ld_r_n & reg8_dest == REG8_PHL) | (is_ld_r_r & reg8_dest == REG8_PHL) | is_call_nn;
endmodule : decode