commit cd2e08e52a768f6c1b8b8146fc7c9c16cb32f8d7
parent b1fb65453377605f224141a3e96679be6891fc0f
Author: Brian Swetland <swetland@frotz.net>
Date: Sun, 29 Jun 2025 13:30:09 -0700
sr32asm: tidy up the parser
- rename expect_...() to parse_...()
- make them return values in a uniform way
- be consistent about when next() is called
- allow ld/st instructions to omit the register (implying x0)
Diffstat:
1 file changed, 76 insertions(+), 80 deletions(-)
diff --git a/softrisc32/src/sr32asm.c b/softrisc32/src/sr32asm.c
@@ -422,139 +422,138 @@ unsigned next(State *state) {
return state->tok;
}
-void require(State *s, unsigned expected) {
+void expect(State *s, unsigned expected) {
if (expected != s->tok) {
die("expected %s, got %s", tnames[expected], tnames[s->tok]);
}
}
-void expect(State *s, unsigned expected) {
- if (expected != next(s)) {
- die("expected %s, got %s", tnames[expected], tnames[s->tok]);
- }
+void require(State *s, unsigned expected) {
+ expect(s, expected);
+ next(s);
}
-unsigned expect_reg(State *s) {
- if (next(s) != tREGISTER) {
- die("expected register, got %s", tnames[s->tok]);
- }
- return s->num;
+void parse_reg(State *s, uint32_t *r) {
+ expect(s, tREGISTER);
+ *r = s->num;
+ next(s);
}
-uint32_t expect_num(State *s) {
- if (next(s) != tNUMBER) {
- die("expected number, got %s", tnames[s->tok]);
- }
- return s->num;
+void parse_num(State *s, uint32_t *n) {
+ expect(s, tNUMBER);
+ *n = s->num;
+ next(s);
}
-// next() advance to next token
-// expect...() advance to next token and fail if wrong kind
-// require...() fail if current token is wrong kind
-// allow...() advance to next token and consume if it matches
-
-void expect_memref(State *s, uint32_t *r, uint32_t *i) {
- if (next(s) == tNUMBER) {
+void parse_memref(State *s, uint32_t *r, uint32_t *i) {
+ if (s->tok == tNUMBER) {
*i = s->num;
- next(s);
+ if (next(s) != tOPAREN) {
+ *r = 0;
+ return;
+ }
} else {
*i = 0;
}
require(s, tOPAREN);
- *r = expect_reg(s);
- expect(s, tCPAREN);
+ parse_reg(s, r);
+ require(s, tCPAREN);
}
-uint32_t expect_rel(State *s, unsigned type) {
- switch (next(s)) {
+void parse_rel(State *s, unsigned type, uint32_t *i) {
+ switch (s->tok) {
case tIDENT:
- return uselabel(s->str, PC, type);
+ *i = uselabel(s->str, PC, type);
+ break;
case tDOT:
- return -4;
+ *i = -4;
+ break;
default:
die("expected address");
- return 0;
}
+ next(s);
}
-void expect_r_c(State *s, uint32_t *one) {
- *one = expect_reg(s);
- expect(s, tCOMMA);
+void parse_r_c(State *s, uint32_t *one) {
+ parse_reg(s, one);
+ require(s, tCOMMA);
}
-void expect_2r(State *s, uint32_t *one, uint32_t *two) {
- expect_r_c(s, one);
- *two = expect_reg(s);
+void parse_2r(State *s, uint32_t *one, uint32_t *two) {
+ parse_r_c(s, one);
+ parse_reg(s, two);
}
-void expect_2r_c(State *s, uint32_t *one, uint32_t *two) {
- expect_2r(s, one, two);
- expect(s, tCOMMA);
+void parse_2r_c(State *s, uint32_t *one, uint32_t *two) {
+ parse_2r(s, one, two);
+ require(s, tCOMMA);
}
int parse_line(State *s) {
uint32_t a, b, t, i, o;
char *name;
-
- unsigned tok = next(s);
- if (tok == tIDENT) {
+ if (s->tok == tIDENT) {
name = strdup(s->str);
setlabel(name, PC);
if (next(s) != tCOLON) {
die("unexpected '%s'\n", name);
}
- tok = next(s);
+ next(s);
}
+
+ unsigned tok = s->tok;
+ next(s);
+
switch (tok) {
case tADD: case tSUB: case tAND: case tOR:
case tXOR: case tSLL: case tSRL: case tSRA:
case tSLT: case tSLTU:
o = tok - tADD;
- expect_2r_c(s, &t, &a);
- b = expect_reg(s);
+ parse_2r_c(s, &t, &a);
+ parse_reg(s, &b);
emit(ins_r(0, b, a, t, o));
break;
case tADDI: case tSUBI: case tANDI: case tORI:
case tXORI: case tSLLI: case tSRLI: case tSRAI:
case tSLTI: case tSLTUI:
o = tok - tADDI;
- expect_2r_c(s, &t, &a);
- b = expect_num(s);
+ parse_2r_c(s, &t, &a);
+ parse_num(s, &b);
emit(ins_i(b, a, t, o));
break;
// todo: mul div
case tBEQ: case tBNE: case tBLT:
case tBLTU: case tBGE: case tBGEU:
o = tok - tBEQ;
- expect_2r_c(s, &a, &b);
- i = expect_rel(s, TYPE_PCREL_S16);
+ parse_2r_c(s, &a, &b);
+ parse_rel(s, TYPE_PCREL_S16, &i);
emit(ins_b(i, a, b, o));
break;
case tLDW: case tLDH: case tLDB: case tLDX:
case tLDHU: case tLDBU:
o = tok - tLDW;
- expect_r_c(s, &t);
- expect_memref(s, &a, &i);
+ parse_r_c(s, &t);
+ parse_memref(s, &a, &i);
emit(ins_l(i, a, t, o));
break;
case tLUI:
case tAUIPC:
o = tok - tLDW;
- expect_r_c(s, &t);
- i = expect_num(s);
+ parse_r_c(s, &t);
+ parse_num(s, &i);
emit(ins_l(i >> 16, 0, t, o));
break;
case tSTW: case tSTH: case tSTB: case tSTX:
o = tok - tSTW;
- expect_r_c(s, &b);
- expect_memref(s, &a, &i);
+ parse_r_c(s, &b);
+ parse_memref(s, &a, &i);
emit(ins_s(i, a, b, o));
break;
case tJAL:
- expect_r_c(s, &t);
- i = expect_rel(s, TYPE_PCREL_S21);
+ parse_r_c(s, &t);
+ parse_rel(s, TYPE_PCREL_S21, &i);
emit(ins_j(i, t, J_JAL));
break;
case tSYSCALL:
- i = expect_num(s);
+ parse_num(s, &i);
emit(ins_j(i, 0, J_SYSCALL));
break;
case tBREAK:
@@ -564,7 +563,7 @@ int parse_line(State *s) {
emit(ins_j(0, 0, J_SYSRET));
break;
case tJALR:
- expect_2r_c(s, &t, &a);
+ parse_2r_c(s, &t, &a);
if (s->tok == tNUMBER) {
emit(ins_i(s->num, a, t, IR_JALR));
} else if (s->tok == tREGISTER) {
@@ -574,7 +573,7 @@ int parse_line(State *s) {
}
break;
case tJR:
- a = expect_reg(s);
+ parse_reg(s, &a);
emit(ins_r(0, 0, a, 0, IR_JALR));
break;
case tRET:
@@ -584,12 +583,12 @@ int parse_line(State *s) {
emit(ins_i(0, 0, 0, IR_ADD));
break;
case tMV:
- expect_2r(s, &t, &a);
+ parse_2r(s, &t, &a);
emit(ins_r(0, 0, a, t, IR_ADD));
break;
case tLI:
- expect_r_c(s, &t);
- i = expect_num(s);
+ parse_r_c(s, &t);
+ parse_num(s, &i);
if (is_signed16(i)) {
emit(ins_i(i, 0, t, IR_ADD));
} else {
@@ -604,18 +603,19 @@ int parse_line(State *s) {
}
break;
case tJ:
- i = expect_rel(s, TYPE_PCREL_S21);
+ parse_rel(s, TYPE_PCREL_S21, &i);
emit(ins_j(i, 0, J_JAL));
break;
case tEQU:
- expect(s, tIDENT);
+ require(s, tIDENT);
name = strdup(s->str);
- setlabel(name, expect_num(s));
+ parse_num(s, &i);
+ setlabel(name, i);
break;
case tWORD:
- do {
- switch (next(s)) {
+ for (;;) {
+ switch (s->tok) {
case tNUMBER:
emit(s->num);
break;
@@ -626,25 +626,20 @@ int parse_line(State *s) {
default:
die("expected constant or symbol");
}
- } while (next(s) == tCOMMA);
- goto end_of_line;
+ if (next(s) != tCOMMA) break;
+ next(s);
+ }
+ break;
// todo: BYTE, HALF, string data
case tEOL:
return 1;
- }
-
- next(s);
-end_of_line:
- switch (s->tok) {
case tEOF:
return 0;
- case tEOL:
- return 1;
- default:
- die("unexpected %s\n", tnames[tok]);
- return 0;
}
+
+ require(s, tEOL);
+ return 1;
}
void assemble(const char *fn) {
@@ -656,6 +651,7 @@ void assemble(const char *fn) {
}
state.next = state.sbuf;
linenumber = 1;
+ next(&state);
while (parse_line(&state)) ;
}
