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Arlet 65C02 WIP: Implement (zp) addressing mode

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Change-Id: I5ae6506c8ad403cc8a6ca2004c09d4df84a7f5df
This commit is contained in:
David Banks
2016-08-01 11:57:23 +01:00
parent d7fdd129b1
commit 5a7224efe0
1 changed files with 22 additions and 4 deletions
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26
cpu_65c02.v
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@@ -219,7 +219,8 @@ parameter
WRITE = 6'd46, // Write memory for read/modify/write
ZP0 = 6'd47, // Z-page - fetch ZP address
ZPX0 = 6'd48, // ZP, X - fetch ZP, and send to ALU (+X)
ZPX1 = 6'd49; // ZP, X - load from memory
ZPX1 = 6'd49, // ZP, X - load from memory
IND0 = 6'd50; // (ZP) - fetch ZP address, and send to ALU (+0)
`ifdef SIM
@@ -240,6 +241,7 @@ always @*
ABSX0: statename = "ABSX0";
ABSX1: statename = "ABSX1";
ABSX2: statename = "ABSX2";
IND0: statename = "IND0";
INDX0: statename = "INDX0";
INDX1: statename = "INDX1";
INDX2: statename = "INDX2";
@@ -887,6 +889,7 @@ always @(posedge clk or posedge reset)
8'b1xx0_1100: state <= ABS0; // X/Y abs
8'b1xxx_1000: state <= REG; // DEY, TYA, ...
8'bxxx0_0001: state <= INDX0;
8'bxxx1_0010: state <= IND0; // (ZP) odd 2 column
8'bxxx0_01xx: state <= ZP0;
8'bxxx0_1001: state <= FETCH; // IMM
8'bxxx0_1101: state <= ABS0; // even E column
@@ -915,6 +918,8 @@ always @(posedge clk or posedge reset)
ABSX1 : state <= (CO | store | write_back) ? ABSX2 : FETCH;
ABSX2 : state <= write_back ? READ : FETCH;
IND0 : state <= INDX1;
INDX0 : state <= INDX1;
INDX1 : state <= INDX2;
INDX2 : state <= INDX3;
@@ -984,6 +989,8 @@ always @(posedge clk)
always @(posedge clk)
if( state == DECODE && RDY )
casex( IR )
8'b0xx10010, // ORA, AND, EOR, ADC (zp)
8'b1x110010, // LDA, SBC (zp)
8'b0xxx1010, // ASLA, INCA, ROLA, DECA, LSRA, PHY, RORA, PLY
8'b0xxxxx01, // ORA, AND, EOR, ADC
8'b100x10x0, // DEY, TYA, TXA, TXS
@@ -1005,7 +1012,9 @@ always @(posedge clk)
8'b1110_1000, // INX
8'b1100_1010, // DEX
8'b1111_1010, // PLX
8'b101x_xx10: // LDX, TAX, TSX
8'b1010_0010, // LDX imm
8'b101x_x110, // LDX
8'b101x_1x10: // LDX, TAX, TSX
dst_reg <= SEL_X;
8'b0x00_1000, // PHP, PHA
@@ -1060,6 +1069,7 @@ always @(posedge clk)
always @(posedge clk)
if( state == DECODE && RDY )
casex( IR )
8'b1001_0010, // STA (zp)
8'b100x_x1x0, // STX, STY
8'b100x_xx01: // STA
store <= 1;
@@ -1101,6 +1111,7 @@ always @(posedge clk )
always @(posedge clk )
if( (state == DECODE || state == BRK0) && RDY )
casex( IR )
8'bx111_0010, // SBC (zp), ADC (zp)
8'bx11x_xx01: // SBC, ADC
adc_sbc <= 1;
@@ -1110,6 +1121,7 @@ always @(posedge clk )
always @(posedge clk )
if( (state == DECODE || state == BRK0) && RDY )
casex( IR )
8'b0111_0010, // ADC (zp)
8'b011x_xx01: // ADC
adc_bcd <= D;
@@ -1129,6 +1141,7 @@ always @(posedge clk )
always @(posedge clk )
if( state == DECODE && RDY )
casex( IR )
8'b1101_0010, // CMP (zp)
8'b11x0_0x00, // CPX, CPY (imm/zp)
8'b11x0_1100, // CPX, CPY (abs)
8'b110x_xx01: // CMP
@@ -1140,7 +1153,8 @@ always @(posedge clk )
always @(posedge clk )
if( state == DECODE && RDY )
casex( IR )
8'b01xx_xx10: // ROR, LSR
8'b01xx_x110, // ROR, LSR
8'b01xx_1x10: // ROR, LSR
shift_right <= 1;
default: shift_right <= 0;
@@ -1166,9 +1180,11 @@ always @(posedge clk )
8'b0010_x100: // BIT zp/abs
op <= OP_AND;
8'b01xx_xx10: // ROR, LSR
8'b01xx_x110, // ROR, LSR
8'b01xx_1x10: // ROR, LSR
op <= OP_A;
8'b11x1_0010, // CMP, SBC (zp)
8'b0011_1010, // DEC A
8'b1000_1000, // DEY
8'b1100_1010, // DEX
@@ -1177,6 +1193,8 @@ always @(posedge clk )
8'b11x0_0x00, // CPX, CPY (imm, zpg)
8'b11x0_1100: op <= OP_SUB;
8'b00x1_0010, // ORA, AND (zp)
8'b0x01_0010, // ORA, EOR (zp)
8'b010x_xx01, // EOR
8'b00xx_xx01: // ORA, AND
op <= { 2'b11, IR[6:5] };