From ddac9a14d06aede874b40b097b30b2e625710600 Mon Sep 17 00:00:00 2001 From: jborza Date: Sat, 27 Apr 2019 13:57:47 +0200 Subject: [PATCH] memory function name refactoring (pop->fetch) --- cpu.c | 32 ++++++++++++-------------------- memory.c | 31 +++++++++++++++++++++---------- memory.h | 4 ++++ 3 files changed, 37 insertions(+), 30 deletions(-) diff --git a/cpu.c b/cpu.c index 2123055..dbe36dc 100644 --- a/cpu.c +++ b/cpu.c @@ -53,9 +53,7 @@ void clear_state(State6502 * state) { state->running = 1; } -byte pop_byte(State6502 * state) { - return state->memory[state->pc++]; -} + void push_byte_to_stack(State6502 * state, byte value) { //stack located between $0100 to $01FF @@ -351,17 +349,11 @@ void PHP_(State6502* state) { push_byte_to_stack(state, flags_value); } -word pop_word(State6502 * state) { - byte low = pop_byte(state); - byte high = pop_byte(state); - word result = (high << 8) | low; - return result; -} int emulate_6502_op(State6502 * state) { byte* opcode = &state->memory[state->pc++]; switch (*opcode) { - case ADC_IMM: ADC(state, pop_byte(state)); break; + case ADC_IMM: ADC(state, fetch_byte(state)); break; case ADC_ZP: ADC(state, get_byte_zero_page(state)); break; case ADC_ZPX: ADC(state, get_byte_zero_page_x(state)); break; case ADC_ABS: ADC(state, get_byte_absolute(state)); break; @@ -369,7 +361,7 @@ int emulate_6502_op(State6502 * state) { case ADC_ABSY: ADC(state, get_byte_absolute_y(state)); break; case ADC_INDX: ADC(state, get_byte_indirect_x(state)); break; case ADC_INDY: ADC(state, get_byte_indirect_y(state)); break; - case AND_IMM: AND(state, pop_byte(state)); break; + case AND_IMM: AND(state, fetch_byte(state)); break; case AND_ZP: AND(state, get_byte_zero_page(state)); break; case AND_ZPX: AND(state, get_byte_zero_page_x(state)); break; case AND_ABS: AND(state, get_byte_absolute(state)); break; @@ -415,7 +407,7 @@ int emulate_6502_op(State6502 * state) { case TYA: state->a = state->y; set_NZ_flags(state, state->a); break; case TSX: state->x = state->sp; set_NZ_flags(state, state->x); break; case TXS: state->sp = state->x; set_NZ_flags(state, state->x); break; - case CMP_IMM: CMP(state, pop_byte(state)); break; //TODO test + case CMP_IMM: CMP(state, fetch_byte(state)); break; //TODO test case CMP_ZP: CMP(state, get_byte_zero_page(state)); break; //TODO test case CMP_ZPX: CMP(state, get_byte_zero_page_x(state)); break; //TODO test case CMP_ABS: CMP(state, get_byte_absolute(state)); break; @@ -423,10 +415,10 @@ int emulate_6502_op(State6502 * state) { case CMP_ABSY: CMP(state, get_byte_absolute_y(state)); break;//TODO test case CMP_INDX: CMP(state, get_byte_indirect_x(state)); break;//TODO test case CMP_INDY: CMP(state, get_byte_indirect_y(state)); break;//TODO test - case CPX_IMM: CPX(state, pop_byte(state)); break;//TODO test + case CPX_IMM: CPX(state, fetch_byte(state)); break;//TODO test case CPX_ZP: CPX(state, get_byte_zero_page(state)); break;//TODO test case CPX_ABS: CPX(state, get_byte_absolute(state)); break;//TODO test - case CPY_IMM: CPY(state, pop_byte(state)); break;//TODO test + case CPY_IMM: CPY(state, fetch_byte(state)); break;//TODO test case CPY_ZP: CPY(state, get_byte_zero_page(state)); break;//TODO test case CPY_ABS: CPY(state, get_byte_absolute(state)); break;//TODO test case DEC_ZP: DEC(state, get_address_zero_page(state)); break; @@ -437,7 +429,7 @@ int emulate_6502_op(State6502 * state) { case DEY: state->y -= 1; set_NZ_flags(state, state->y); break; case INX: state->x += 1; set_NZ_flags(state, state->x); break; case INY: state->y += 1; set_NZ_flags(state, state->y); break; - case EOR_IMM: EOR(state, pop_byte(state)); break; + case EOR_IMM: EOR(state, fetch_byte(state)); break; case EOR_ZP: EOR(state, get_byte_zero_page(state)); break; case EOR_ZPX: EOR(state, get_byte_zero_page_x(state)); break; case EOR_ABS: EOR(state, get_byte_absolute(state)); break; @@ -452,7 +444,7 @@ int emulate_6502_op(State6502 * state) { case JMP_ABS: JMP(state, get_address_absolute(state)); break; case JMP_IND: JMP(state, get_address_indirect_jmp(state)); break; case JSR_ABS: JSR(state, get_address_absolute(state)); break; - case LDA_IMM: LDA(state, pop_byte(state)); break; + case LDA_IMM: LDA(state, fetch_byte(state)); break; case LDA_ZP: LDA(state, get_byte_zero_page(state)); break; case LDA_ZPX: LDA(state, get_byte_zero_page_x(state)); break; case LDA_ABS: LDA(state, get_byte_absolute(state)); break; @@ -460,12 +452,12 @@ int emulate_6502_op(State6502 * state) { case LDA_ABSY: LDA(state, get_byte_absolute_y(state)); break; case LDA_INDX: LDA(state, get_byte_indirect_x(state)); break; case LDA_INDY: LDA(state, get_byte_indirect_y(state)); break; - case LDX_IMM: LDX(state, pop_byte(state)); break; + case LDX_IMM: LDX(state, fetch_byte(state)); break; case LDX_ZP: LDX(state, get_byte_zero_page(state)); break; case LDX_ZPY: LDX(state, get_byte_zero_page_y(state)); break; case LDX_ABS: LDX(state, get_byte_absolute(state)); break; case LDX_ABSY: LDX(state, get_byte_absolute_y(state)); break; - case LDY_IMM: LDY(state, pop_byte(state)); break; + case LDY_IMM: LDY(state, fetch_byte(state)); break; case LDY_ZP: LDY(state, get_byte_zero_page(state)); break; case LDY_ZPX: LDY(state, get_byte_zero_page_x(state)); break; case LDY_ABS: LDY(state, get_byte_absolute(state)); break; @@ -475,7 +467,7 @@ int emulate_6502_op(State6502 * state) { case LSR_ZPX: LSR_MEM(state, get_address_zero_page_x(state)); break; case LSR_ABS: LSR_MEM(state, get_address_absolute(state)); break; case LSR_ABSX: LSR_MEM(state, get_address_absolute_x(state)); break; - case ORA_IMM: ORA(state, pop_byte(state)); break; + case ORA_IMM: ORA(state, fetch_byte(state)); break; case ORA_ZP: ORA(state, get_byte_zero_page(state)); break; case ORA_ZPX: ORA(state, get_byte_zero_page_x(state)); break; case ORA_ABS: ORA(state, get_byte_absolute(state)); break; @@ -493,7 +485,7 @@ int emulate_6502_op(State6502 * state) { case ROR_ZPX: ROR_MEM(state, get_address_zero_page_x(state)); break; case ROR_ABS: ROR_MEM(state, get_address_absolute(state)); break; case ROR_ABSX: ROR_MEM(state, get_address_absolute_x(state)); break; - case SBC_IMM: SBC(state, pop_byte(state)); break; + case SBC_IMM: SBC(state, fetch_byte(state)); break; case SBC_ZP: SBC(state, get_byte_zero_page(state)); break; case SBC_ZPX: SBC(state, get_byte_zero_page_x(state)); break; case SBC_ABS: SBC(state, get_byte_absolute(state)); break; diff --git a/memory.c b/memory.c index 1d35808..bfbc349 100644 --- a/memory.c +++ b/memory.c @@ -1,11 +1,22 @@ #include "memory.h" +byte fetch_byte(State6502* state) { + return state->memory[state->pc++]; +} + +word fetch_word(State6502* state) { + byte low = fetch_byte(state); + byte high = fetch_byte(state); + word result = (high << 8) | low; + return result; +} + word read_word(State6502* state, word address) { return state->memory[address] | state->memory[address + 1] << 8; } word get_address_zero_page(State6502* state) { - return pop_byte(state); + return fetch_byte(state); } byte get_byte_zero_page(State6502* state) { @@ -15,7 +26,7 @@ byte get_byte_zero_page(State6502* state) { word get_address_zero_page_x(State6502* state) { //address is zero page, so wraparound byte - byte address = pop_byte(state) + state->x; + byte address = fetch_byte(state) + state->x; return address; } @@ -25,7 +36,7 @@ byte get_byte_zero_page_x(State6502* state) { word get_address_zero_page_y(State6502* state) { //address is zero page, so wraparound byte - byte address = pop_byte(state) + state->y; + byte address = fetch_byte(state) + state->y; return address; } @@ -35,7 +46,7 @@ byte get_byte_zero_page_y(State6502* state) { word get_address_absolute(State6502* state) { //absolute indexed, 16 bits - word address = pop_word(state); + word address = fetch_word(state); return address; } @@ -47,7 +58,7 @@ byte get_byte_absolute(State6502* state) word get_address_absolute_x(State6502* state) { //absolute added with the contents of x register - word address = pop_word(state) + state->x; + word address = fetch_word(state) + state->x; return address; } @@ -57,7 +68,7 @@ byte get_byte_absolute_x(State6502* state) { word get_address_absolute_y(State6502* state) { //absolute added with the contents of x register - word address = pop_word(state) + state->y; + word address = fetch_word(state) + state->y; return address; } @@ -68,7 +79,7 @@ byte get_byte_absolute_y(State6502* state) { word get_address_indirect_jmp(State6502* state) { //AN INDIRECT JUMP MUST NEVER USE A VECTOR BEGINNING ON THE LAST BYTE OF A PAGE - word indirect_address = pop_word(state); + word indirect_address = fetch_word(state); if ((indirect_address & 0xFF) == 0xFF) { //avoid crossing the page boundary return state->memory[indirect_address] | state->memory[indirect_address - 0xFF] << 8; @@ -81,7 +92,7 @@ word get_address_indirect_jmp(State6502* state) { word get_address_indirect_x(State6502* state) { //pre-indexed indirect with the X register //zero-page address is added to x register - byte indirect_address = pop_byte(state) + state->x; + byte indirect_address = fetch_byte(state) + state->x; //pointing to address of a word holding the address of the operand word address = read_word(state, indirect_address); return address; @@ -95,7 +106,7 @@ byte get_byte_indirect_x(State6502* state) { word get_address_indirect_y(State6502* state) { //post-indexed indirect //zero-page address as an argument - byte indirect_address = pop_byte(state); + byte indirect_address = fetch_byte(state); //the address and the following byte is read as a word, adding Y register word address = read_word(state, indirect_address) + state->y; return address; @@ -106,6 +117,6 @@ byte get_byte_indirect_y(State6502* state) { } word get_address_relative(State6502* state) { - int8_t address = (int8_t)pop_byte(state); + int8_t address = (int8_t)fetch_byte(state); return state->pc + address; } \ No newline at end of file diff --git a/memory.h b/memory.h index 2911644..5822322 100644 --- a/memory.h +++ b/memory.h @@ -1,6 +1,10 @@ #pragma once #include "state.h" +byte fetch_byte(State6502* state); + +word fetch_word(State6502* state); + word read_word(State6502* state, word address); word get_address_zero_page(State6502* state);