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Remove implementation defined behaviour.

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This commit is contained in:
Bernd Boeckmann
2022-10-11 23:20:27 +02:00
parent 0226201675
commit 94fda26545
1 changed files with 19 additions and 26 deletions
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45
asm6502.c
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@@ -14,8 +14,8 @@
char *text = NULL;
char *code = NULL;
u16 pc = 0; /* program counter */
u16 oc = 0; /* output counter */
u16 pc = 0; /* program counter */
u16 oc = 0; /* output counter */
int errors = 0;
#define VALUE_DEFINED 0x40
@@ -204,21 +204,8 @@ u16 digit(const char *p)
return (u16)(*p + 10 - 'a');
}
/*#define skipw(p) while (((*(p)) == ' ') || ((*(p)) == '\t')) { (p)++; }*/
/*#define skipnext(p) (p)++; while (((*(p)) == ' ') || ((*(p)) == '\t')) { (p)++; }*/
/*#define skipcomment(p) if (*(p) == ';') { \
(p)++; \
while((*(p) != 0x0d) && (*(p) != 0x0a) && (*(p) != 0)) (p)++; \
}*/
/*#define skipwc(p) { skipw((p)); skipcomment((p)); }*/
/*#define skipeol(p) if (*(p) == 0x0d) (p)++; if (*(p) == 0x0a) (p)++;*/
#define iseol(p) (((p) == 0x0a) || ((p) == 0x0d))
#define isend(p) (((!(p)) || (p) == 0x0a) || ((p) == 0x0d))
/*#define skipl(p) { while (!isend(*(p))) (p)++; }*/
void skipeol(char **p)
{
@@ -269,7 +256,6 @@ value number(char **p)
typ = ((*p-pt)>3) ? TYPE_WORD : NUM_TYPE(num.v);
SET_TYPE(num, typ);
SET_DEFINED(num);
/*printf("t: %x\n", num.t);*/
}
else {
if (!isdigit(**p)) error(ERR_NUM);
@@ -335,6 +321,12 @@ value primary(char **p)
res.v = 0;
res.t = 0;
}
else if (**p == '@') {
(*p)++;
res.v = pc;
SET_TYPE(res, TYPE_WORD);
SET_DEFINED(res);
}
else if (isalpha(**p)) {
ident(p, id);
sym = lookup(id);
@@ -446,12 +438,6 @@ idesc *getidesc(const char *p)
return NULL;
}
/*#define EMIT_B(b) printf("%02x ", (int)(b));*/
/*#define EMIT_B(b) code[oc++] = (b)
#define EMIT_0(i, a) EMIT_B((i).op[a])
#define EMIT_1(i, a, o) { EMIT_B((i).op[a]); EMIT_B(o); }
#define EMIT_2(i, a, o) { EMIT_B((i).op[a]); EMIT_B((o) & 0xff); EMIT_B((o) >> 8); }*/
void emit_b(u8 b, int pass)
{
if (pass == 2) {
@@ -519,14 +505,21 @@ int instruction_imm(char **p, int pass, idesc *instr)
int instruction_rel(char **p, int pass, idesc *instr, value v)
{
int am = AM_REL;
int off;
u16 pct = pc + 2u;
u16 off;
off = (v.v - pc - 2);
/* relative branch offsets are in 2-complement */
/* have to calculate it by hand avoiding implementation defined behaviour */
/* using unsigned int because int may not be in 2-complement */
if (pass == 2) {
if (UNDEFINED(v)) error(ERR_UNDEF);
if ((off > 127) || (off < -128)) error(ERR_RELRNG);
if ((v.v >= pct) && ((u16)(v.v - pct) > 127u)) error(ERR_RELRNG);
else if ((pct > v.v) && ((u16)(pct - v.v) > 128u)) error(ERR_RELRNG);
}
emit_1(instr, am, off & 0xff, pass);
if (v.v >= pct) off = v.v - pct;
else off = (~0u) - (pct - v.v - 1u);
emit_1(instr, am, off & 0xffu, pass);
return am;
}