Clean up the fetch interface

This removes a relatively expensive compare in a hot spot, and some
dodgy integer arith

5 files changed, 16 insertions, 19 deletions

diff --git a/src/ls_goto.c b/src/ls_goto.c
index 1bc74f9..f941620 100644
--- a/src/ls_goto.c
+++ b/src/ls_goto.c
@@ -161,7 +161,7 @@ static bool _rewind_line(ls_t * self)
 
 	for (;;)
 	{
-		unsigned char ch = ls_fetch(self, pc);
+		unsigned char ch = ls_fetch_at(self, pc);
 
 		if (ch == '\n')
 		{
diff --git a/src/ls_internal.c b/src/ls_internal.c
index 78bab75..659ec91 100644
--- a/src/ls_internal.c
+++ b/src/ls_internal.c
@@ -116,14 +116,12 @@ void ls_throw_err(ls_t * self, ls_error_t e)
 	}
 }
 
-ls_uchar ls_fetch_rel(ls_t * self, int offset)
+ls_uchar ls_fetch(ls_t * self)
 {
-	if (self->_pc + offset > UINT16_MAX || self->_pc + offset < 0)
-		ls_throw_err(self, LS_INTERNAL_ERROR);
-	return ls_fetch(self, (ls_addr_t)(self->_pc + offset));
+	return ls_fetch_at(self, self->_pc);
 }
 
-ls_uchar ls_fetch(ls_t * self, ls_addr_t pc)
+ls_uchar ls_fetch_at(ls_t * self, ls_addr_t pc)
 {
 	int rc = self->fetcher(self->fetcher_arg, pc);
 	if (rc == -LS_NO_MORE_PROGRAM)
diff --git a/src/ls_internal.h b/src/ls_internal.h
index 524f5b4..6a66de0 100644
--- a/src/ls_internal.h
+++ b/src/ls_internal.h
@@ -122,14 +122,13 @@ ls_kw_t ls_convert_kw(char const * word);
 /// is LS_OK, no throw occurs.
 void ls_throw_err(ls_t * self, ls_error_t e);
 
-/// Fetch a character, relative to the current one. Throws if the fetcher
-/// returns an error other than LS_NO_PROGRAM. If there is no character,
-/// returns nul.
-ls_uchar ls_fetch_rel(ls_t * self, int offset);
+/// Fetch the current character. Throws if the fetcher returns an error other
+/// than LS_NO_PROGRAM. If there is no character, returns nul.
+ls_uchar ls_fetch(ls_t * self);
 
 /// Fetch a character at a specific location. If there is no character, returns
 /// nul.
-ls_uchar ls_fetch(ls_t * self, ls_addr_t pc);
+ls_uchar ls_fetch_at(ls_t * self, ls_addr_t pc);
 
 /// Allocate from the pool, throwing LS_OUT_OF_MEMORY if not possible. Always
 /// returns a valid pointer (or doesn't return)
diff --git a/src/ls_kw_impl_PRINT.c b/src/ls_kw_impl_PRINT.c
index a854bb3..1294219 100644
--- a/src/ls_kw_impl_PRINT.c
+++ b/src/ls_kw_impl_PRINT.c
@@ -44,7 +44,7 @@ void ls_kw_fun_PRINT(ls_t * self)
 			     i <= self->_token.string[1];
 			     i++)
 			{
-				unsigned char c = ls_fetch(self, i);
+				unsigned char c = ls_fetch_at(self, i);
 				fprintf(file, "%c", c);
 			}
 			break;
diff --git a/src/ls_lex.c b/src/ls_lex.c
index 95c9045..b9370e3 100644
--- a/src/ls_lex.c
+++ b/src/ls_lex.c
@@ -58,7 +58,7 @@ ls_token_t ls_lex(ls_t * self)
 	bool skip_rem = false;
 
 	do {
-		ch[0] = ls_fetch_rel(self, 0);
+		ch[0] = ls_fetch(self);
 		ch_kind = _ident_ch_kind(ch[0]);
 		self->_pc++;
 
@@ -68,7 +68,7 @@ ls_token_t ls_lex(ls_t * self)
 			skip_rem = false;
 	} while (ch_kind == CH_KIND_SPACE || skip_rem);
 
-	ch[1] = ls_fetch_rel(self, 0);
+	ch[1] = ls_fetch(self);
 
 	switch (ch_kind)
 	{
@@ -126,7 +126,7 @@ ls_token_t ls_lex(ls_t * self)
 void ls_consume_to_eol(ls_t * self)
 {
 	for (;;) {
-		ls_uchar uch = ls_fetch_rel(self, 0);
+		ls_uchar uch = ls_fetch(self);
 
 		if (uch == 0 || uch == '\n')
 			return;
@@ -284,7 +284,7 @@ static ls_token_t _lex_num(ls_t * self, ls_uchar ch[2])
 			nch = 1;
 
 		self->_pc = (ls_addr_t)(self->_pc + nch - 1);
-		ch[0] = ls_fetch_rel(self, 0);
+		ch[0] = ls_fetch(self);
 		self->_pc++;
 	}
 
@@ -317,7 +317,7 @@ static ls_token_t _lex_num(ls_t * self, ls_uchar ch[2])
 			break;
 		}
 
-		ch[0] = ls_fetch_rel(self, 0);
+		ch[0] = ls_fetch(self);
 		self->_pc++;
 
 		if (digit >= radix)
@@ -340,7 +340,7 @@ static ls_token_t _lex_word(ls_t * self, ls_uchar ch[2])
 		if (i < sizeof(self->_token.word) - 1 && ch[0] <= CHAR_MAX)
 			self->_token.word[i] = (char) ch[0];
 
-		ch[0] = ls_fetch_rel(self, 0);
+		ch[0] = ls_fetch(self);
 		ch_kind_t ch_kind = _ident_ch_kind(ch[0]);
 		self->_pc++;
 
@@ -408,7 +408,7 @@ static ls_token_t _lex_str(ls_t * self, ls_uchar ch[2])
 	self->_token.string[0] = self->_pc;
 	for (;;)
 	{
-		ch[0] = ls_fetch_rel(self, 0);
+		ch[0] = ls_fetch(self);
 		if (ch[0] == '"')
 		{
 			self->_token.string[1] = (ls_addr_t)(self->_pc - 1);