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Fixed cycle timing for multi-byte NOP instructions

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This commit is contained in:
Rob McMullen 2017-12-18 22:50:41 -08:00
parent 454e33269a
commit 2ae87bf12e
1 changed files with 11 additions and 1 deletions
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12
6502.c
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@ -316,7 +316,9 @@ static void inst_LSR()
static void inst_NOP() static void inst_NOP()
{ {
// nothing // thrown away, just used to compute any extra cycles for the multi-byte
// NOP statements
read_ptr();
} }
static void inst_ORA() static void inst_ORA()
@ -483,6 +485,13 @@ static void inst_TYA()
/* Addressing Implementations */ /* Addressing Implementations */
uint8_t * get_IMPL()
{
// dummy implementation; for completeness necessary for cycle counting NOP
// instructions
return &memory[0];
}
uint8_t * get_IMM() uint8_t * get_IMM()
{ {
return &memory[(uint16_t) (PC+1)]; return &memory[(uint16_t) (PC+1)];
@ -627,6 +636,7 @@ void init_tables() // this is only done at runtime to improve code readability.
get_ptr[ABSX] = get_ABSX; get_ptr[ABSX] = get_ABSX;
get_ptr[ABSY] = get_ABSY; get_ptr[ABSY] = get_ABSY;
get_ptr[IMM] = get_IMM; get_ptr[IMM] = get_IMM;
get_ptr[IMPL] = get_IMPL;
get_ptr[IND] = get_IND; get_ptr[IND] = get_IND;
get_ptr[XIND] = get_XIND; get_ptr[XIND] = get_XIND;
get_ptr[INDY] = get_INDY; get_ptr[INDY] = get_INDY;