Revamp pdf lexing code

A huge amount (20%+ on some files) of our runtime is spent in
fz_atof. A survey of results on the net suggests we will get
much better speed by writing our own atof.

Part of the job of doing this involves parsing the string to
identify the component parts of the number - ludicrously, we
are already doing this as part of the lexing process, so it
would make sense to do the atoi/atof as part of this process.

In order to do this, we need somewhere to store the lexed
results; rather than add a float * and an int * to every single
pdf_lex call, we generalise the calls to pass a pdf_lexbuf *
pointer instead of separate buffer/max/string length pointers.
This should help us overall.

1 files changed, 24 insertions, 23 deletions

diff --git a/pdf/pdf_repair.c b/pdf/pdf_repair.c
index 0dc0e132..c70df3e2 100644
--- a/pdf/pdf_repair.c
+++ b/pdf/pdf_repair.c
@@ -13,11 +13,10 @@ struct entry
 };
 
 static void
-pdf_repair_obj(fz_stream *file, char *buf, int cap, int *stmofsp, int *stmlenp, fz_obj **encrypt, fz_obj **id)
+pdf_repair_obj(fz_stream *file, pdf_lexbuf *buf, int *stmofsp, int *stmlenp, fz_obj **encrypt, fz_obj **id)
 {
 	int tok;
 	int stm_len;
-	int len;
 	int n;
 	fz_context *ctx = file->ctx;
 
@@ -26,7 +25,7 @@ pdf_repair_obj(fz_stream *file, char *buf, int cap, int *stmofsp, int *stmlenp,
 
 	stm_len = 0;
 
-	tok = pdf_lex(file, buf, cap, &len);
+	tok = pdf_lex(file, buf);
 	/* RJW: "cannot parse object" */
 	if (tok == PDF_TOK_OPEN_DICT)
 	{
@@ -35,7 +34,7 @@ pdf_repair_obj(fz_stream *file, char *buf, int cap, int *stmofsp, int *stmlenp,
 		/* Send NULL xref so we don't try to resolve references */
 		fz_try(ctx)
 		{
-			dict = pdf_parse_dict(NULL, file, buf, cap);
+			dict = pdf_parse_dict(NULL, file, buf);
 		}
 		fz_catch(ctx)
 		{
@@ -79,13 +78,13 @@ pdf_repair_obj(fz_stream *file, char *buf, int cap, int *stmofsp, int *stmlenp,
 		tok != PDF_TOK_EOF &&
 		tok != PDF_TOK_INT )
 	{
-		tok = pdf_lex(file, buf, cap, &len);
+		tok = pdf_lex(file, buf);
 		/* RJW: "cannot scan for endobj or stream token" */
 	}
 
 	if (tok == PDF_TOK_INT)
 	{
-		while (len-- > 0)
+		while (buf->len-- > 0)
 			fz_unread_byte(file);
 	}
 	else if (tok == PDF_TOK_STREAM)
@@ -106,7 +105,7 @@ pdf_repair_obj(fz_stream *file, char *buf, int cap, int *stmofsp, int *stmlenp,
 			fz_seek(file, *stmofsp + stm_len, 0);
 			fz_try(ctx)
 			{
-				tok = pdf_lex(file, buf, cap, &len);
+				tok = pdf_lex(file, buf);
 			}
 			fz_catch(ctx)
 			{
@@ -117,23 +116,23 @@ pdf_repair_obj(fz_stream *file, char *buf, int cap, int *stmofsp, int *stmlenp,
 			fz_seek(file, *stmofsp, 0);
 		}
 
-		n = fz_read(file, (unsigned char *) buf, 9);
+		n = fz_read(file, (unsigned char *) buf->scratch, 9);
 		if (n < 0)
 			fz_throw(ctx, "cannot read from file");
 
-		while (memcmp(buf, "endstream", 9) != 0)
+		while (memcmp(buf->scratch, "endstream", 9) != 0)
 		{
 			c = fz_read_byte(file);
 			if (c == EOF)
 				break;
-			memmove(buf, buf + 1, 8);
-			buf[8] = c;
+			memmove(&buf->scratch[0], &buf->scratch[1], 8);
+			buf->scratch[8] = c;
 		}
 
 		*stmlenp = fz_tell(file) - *stmofsp - 9;
 
 atobjend:
-		tok = pdf_lex(file, buf, cap, &len);
+		tok = pdf_lex(file, buf);
 		/* RJW: "cannot scan for endobj token" */
 		if (tok != PDF_TOK_ENDOBJ)
 			fz_warn(ctx, "object missing 'endobj' token");
@@ -147,11 +146,13 @@ pdf_repair_obj_stm(pdf_document *xref, int num, int gen)
 	fz_stream *stm = NULL;
 	int tok;
 	int i, n, count;
-	char buf[256];
 	fz_context *ctx = xref->ctx;
+	pdf_lexbuf buf;
 
 	fz_var(stm);
 
+	buf.size = PDF_LEXBUF_SMALL;
+
 	fz_try(ctx)
 	{
 		obj = pdf_load_object(xref, num, gen);
@@ -164,11 +165,11 @@ pdf_repair_obj_stm(pdf_document *xref, int num, int gen)
 
 		for (i = 0; i < count; i++)
 		{
-			tok = pdf_lex(stm, buf, sizeof buf, &n);
+			tok = pdf_lex(stm, &buf);
 			if (tok != PDF_TOK_INT)
 				fz_throw(ctx, "corrupt object stream (%d %d R)", num, gen);
 
-			n = atoi(buf);
+			n = buf.i;
 			if (n >= xref->len)
 				pdf_resize_xref(xref, n + 1);
 
@@ -179,7 +180,7 @@ pdf_repair_obj_stm(pdf_document *xref, int num, int gen)
 			xref->table[n].obj = NULL;
 			xref->table[n].type = 'o';
 
-			tok = pdf_lex(stm, buf, sizeof buf, &n);
+			tok = pdf_lex(stm, &buf);
 			if (tok != PDF_TOK_INT)
 				fz_throw(ctx, "corrupt object stream (%d %d R)", num, gen);
 		}
@@ -195,7 +196,7 @@ pdf_repair_obj_stm(pdf_document *xref, int num, int gen)
 }
 
 void
-pdf_repair_xref(pdf_document *xref, char *buf, int bufsize)
+pdf_repair_xref(pdf_document *xref, pdf_lexbuf *buf)
 {
 	fz_obj *dict, *obj;
 	fz_obj *length;
@@ -234,14 +235,14 @@ pdf_repair_xref(pdf_document *xref, char *buf, int bufsize)
 		list = fz_malloc_array(ctx, listcap, sizeof(struct entry));
 
 		/* look for '%PDF' version marker within first kilobyte of file */
-		n = fz_read(xref->file, (unsigned char *)buf, MIN(bufsize, 1024));
+		n = fz_read(xref->file, (unsigned char *)buf->scratch, MIN(buf->size, 1024));
 		if (n < 0)
 			fz_throw(ctx, "cannot read from file");
 
 		fz_seek(xref->file, 0, 0);
 		for (i = 0; i < n - 4; i++)
 		{
-			if (memcmp(buf + i, "%PDF", 4) == 0)
+			if (memcmp(&buf->scratch[i], "%PDF", 4) == 0)
 			{
 				fz_seek(xref->file, i + 8, 0); /* skip "%PDF-X.Y" */
 				break;
@@ -263,7 +264,7 @@ pdf_repair_xref(pdf_document *xref, char *buf, int bufsize)
 
 			fz_try(ctx)
 			{
-				tok = pdf_lex(xref->file, buf, bufsize, &n);
+				tok = pdf_lex(xref->file, buf);
 			}
 			fz_catch(ctx)
 			{
@@ -276,14 +277,14 @@ pdf_repair_xref(pdf_document *xref, char *buf, int bufsize)
 				numofs = genofs;
 				num = gen;
 				genofs = tmpofs;
-				gen = atoi(buf);
+				gen = buf->i;
 			}
 
 			else if (tok == PDF_TOK_OBJ)
 			{
 				fz_try(ctx)
 				{
-					pdf_repair_obj(xref->file, buf, bufsize, &stm_ofs, &stm_len, &encrypt, &id);
+					pdf_repair_obj(xref->file, buf, &stm_ofs, &stm_len, &encrypt, &id);
 				}
 				fz_catch(ctx)
 				{
@@ -318,7 +319,7 @@ pdf_repair_xref(pdf_document *xref, char *buf, int bufsize)
 			{
 				fz_try(ctx)
 				{
-					dict = pdf_parse_dict(xref, xref->file, buf, bufsize);
+					dict = pdf_parse_dict(xref, xref->file, buf);
 				}
 				fz_catch(ctx)
 				{