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Add support for PHX, PHY, PLX, PLY

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These instructions allow you to push and pull (pop) the X and Y
registers via the stack.
This commit is contained in:
Peter Evans 2018-02-21 23:32:57 -06:00
parent f9a277e7bc
commit 8e1ab0e950
5 changed files with 75 additions and 0 deletions
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4
include/mos6502.enums.h
View File

@ -105,8 +105,12 @@ enum instruction {
ORA, // OR with Accumulator
PHA, // PusH Accumulator
PHP, // PusH Predicate register
PHX, // PusH X register
PHY, // PusH Y register
PLA, // PulL Accumulator
PLP, // PulL Predicate register
PLX, // PulL X register
PLY, // PulL Y register
ROL, // ROtate Left
ROR, // ROtate Right
RTI, // ReTurn from Interrupt

4
include/mos6502.h
View File

@ -214,8 +214,12 @@ DECL_INST(nop);
DECL_INST(ora);
DECL_INST(pha);
DECL_INST(php);
DECL_INST(phx);
DECL_INST(phy);
DECL_INST(pla);
DECL_INST(plp);
DECL_INST(plx);
DECL_INST(ply);
DECL_INST(rol);
DECL_INST(ror);
DECL_INST(rti);

4
src/mos6502.dis.c
View File

@ -81,8 +81,12 @@ static char *instruction_strings[] = {
"ORA",
"PHA",
"PHP",
"PHX",
"PHY",
"PLA",
"PLP",
"PLX",
"PLY",
"ROL",
"ROR",
"RTI",

33
src/mos6502.loadstor.c
View File

@ -52,6 +52,23 @@ DEFINE_INST(php)
mos6502_push_stack(cpu, cpu->P);
}
/*
* Push the X register onto the stack. Sadly, this does not summon a
* phoenix to assist you in hours of need.
*/
DEFINE_INST(phx)
{
mos6502_push_stack(cpu, cpu->X);
}
/*
* Push the Y register onto the stack
*/
DEFINE_INST(phy)
{
mos6502_push_stack(cpu, cpu->Y);
}
/*
* Here we pop the stack (or "pull" it), and assign to the accumulator.
*/
@ -71,6 +88,22 @@ DEFINE_INST(plp)
cpu->P = mos6502_pop_stack(cpu);
}
/*
* Pop from the stack and assign that byte to the X register
*/
DEFINE_INST(plx)
{
cpu->X = mos6502_pop_stack(cpu);
}
/*
* Pop from the stack and assign that byte to the Y register
*/
DEFINE_INST(ply)
{
cpu->Y = mos6502_pop_stack(cpu);
}
/*
* The STA instruction assigns the value of the accumulator to a given
* address in memory. (That is to say, it "stores" it.)

30
tests/mos6502.loadstor.c
View File

@ -40,6 +40,20 @@ Test(mos6502_loadstor, php)
cr_assert_eq(mos6502_get(cpu, 0x01ff), 0x43);
}
Test(mos6502_loadstor, phx)
{
cpu->X = 123;
mos6502_handle_phx(cpu, 0);
cr_assert_eq(mos6502_get(cpu, 0x01ff), 123);
}
Test(mos6502_loadstor, phy)
{
cpu->Y = 234;
mos6502_handle_phy(cpu, 0);
cr_assert_eq(mos6502_get(cpu, 0x01ff), 234);
}
Test(mos6502_loadstor, pla)
{
mos6502_push_stack(cpu, 0x0033);
@ -56,6 +70,22 @@ Test(mos6502_loadstor, plp)
cr_assert_eq(cpu->P, 0x52);
}
Test(mos6502_loadstor, plx)
{
mos6502_push_stack(cpu, 87);
mos6502_handle_plx(cpu, 0);
cr_assert_eq(cpu->X, 87);
}
Test(mos6502_loadstor, ply)
{
mos6502_push_stack(cpu, 44);
mos6502_handle_ply(cpu, 0);
cr_assert_eq(cpu->Y, 44);
}
Test(mos6502_loadstor, sta)
{
cpu->A = 123;