diff --git a/fmt.h b/fmt.h
index 6dbda3d..9261829 100644
--- a/fmt.h
+++ b/fmt.h
@@ -10,13 +10,15 @@
 #include <sys/types.h>
 /* for byte_copy */
 #include "byte.h"
-/* for add_of */
-#include "rangecheck.h"
 
 #ifdef __cplusplus
 extern "C" {
 #endif
 
+#ifndef __pure__
+#define __pure__
+#endif
+
 #define FMT_LONG  41 /* enough space to hold -2^127 in decimal, plus \0 */
 #define FMT_ULONG 40 /* enough space to hold 2^128 - 1 in decimal, plus \0 */
 #define FMT_8LONG 44 /* enough space to hold 2^128 - 1 in octal, plus \0 */
@@ -44,31 +46,31 @@ extern "C" {
 /* convert signed src integer -23 to ASCII '-','2','3', return number of
  * bytes of value in output format (3 in this example).
  * If dest is not NULL, write result to dest */
-size_t fmt_long(char *dest,signed long src);
+size_t fmt_long(char *dest,signed long src) __pure__;
 
 /* convert unsigned src integer 23 to ASCII '2','3', return number of
  * bytes of value in output format (2 in this example).
  * If dest is not NULL, write result to dest */
-size_t fmt_ulong(char *dest,unsigned long src);
+size_t fmt_ulong(char *dest,unsigned long src) __pure__;
 
 /* convert unsigned src integer 0x23 to ASCII '2','3', return number of
  * bytes of value in output format (2 in this example).
  * If dest is not NULL, write result to dest */
-size_t fmt_xlong(char *dest,unsigned long src);
+size_t fmt_xlong(char *dest,unsigned long src) __pure__;
 
 /* convert unsigned src integer 023 to ASCII '2','3', return number of
  * bytes of value in output format (2 in this example).
  * If dest is not NULL, write result to dest */
-size_t fmt_8long(char *dest,unsigned long src);
+size_t fmt_8long(char *dest,unsigned long src) __pure__;
 
 /* like fmt_long but for long long */
-size_t fmt_longlong(char *dest,signed long long src);
+size_t fmt_longlong(char *dest,signed long long src) __pure__;
 
 /* like fmt_ulong but for unsigned long long */
-size_t fmt_ulonglong(char *dest,unsigned long long src);
+size_t fmt_ulonglong(char *dest,unsigned long long src) __pure__;
 
 /* like fmt_xlong but for unsigned long long */
-size_t fmt_xlonglong(char *dest,unsigned long long src);
+size_t fmt_xlonglong(char *dest,unsigned long long src) __pure__;
 
 #define fmt_uint(dest,src) fmt_ulong(dest,src)
 #define fmt_int(dest,src) fmt_long(dest,src)
@@ -79,22 +81,22 @@ size_t fmt_xlonglong(char *dest,unsigned long long src);
  * Does not truncate! */
 /* fmt_ulong0(buf,23,4) -> '0','0','2','3' return 4 */
 /* fmt_ulong0(buf,234,2) -> '2','3','4', return 3 */
-size_t fmt_ulong0(char *,unsigned long src,size_t padto);
+size_t fmt_ulong0(char *,unsigned long src,size_t padto) __pure__;
 
 #define fmt_uint0(buf,src,padto) fmt_ulong0(buf,src,padto)
 
 /* convert src double 1.7 to ASCII '1','.','7', return length.
  * If dest is not NULL, write result to dest */
-size_t fmt_double(char *dest, double d,int max,int prec);
+size_t fmt_double(char *dest, double d,int max,int prec) __pure__;
 
 /* if src is negative, write '-' and return 1.
  * if src is positive, write '+' and return 1.
  * otherwise return 0 */
-size_t fmt_plusminus(char *dest,int src);
+size_t fmt_plusminus(char *dest,int src) __pure__;
 
 /* if src is negative, write '-' and return 1.
  * otherwise return 0. */
-size_t fmt_minus(char *dest,int src);
+size_t fmt_minus(char *dest,int src) __pure__;
 
 /* copy str to dest until \0 byte, return number of copied bytes. */
 /* fmt_str(NULL,str) == strlen(str) */
@@ -106,11 +108,11 @@ size_t fmt_minus(char *dest,int src);
  * This is more efficient because strcat needs to scan the string to
  * find the end and append.
  */
-size_t fmt_str(char *dest,const char *src);
+size_t fmt_str(char *dest,const char *src) __pure__;
 
 /* copy str to dest until \0 byte or limit bytes copied.
  * return number of copied bytes. */
-size_t fmt_strn(char *dest,const char *src,size_t limit);
+size_t fmt_strn(char *dest,const char *src,size_t limit) __pure__;
 
 /* copy n bytes from src to dest, return n */
 static inline size_t fmt_copybytes(char* dest,const char* src,size_t n) {
@@ -122,66 +124,56 @@ static inline size_t fmt_copybytes(char* dest,const char* src,size_t n) {
  * write padlen-srclen spaces, if that is >= 0.  Then copy srclen
  * characters from src.  Truncate only if total length is larger than
  * maxlen.  Return number of characters written. */
-size_t fmt_pad(char* dest,const char* src,size_t srclen,size_t padlen,size_t maxlen);
+size_t fmt_pad(char* dest,const char* src,size_t srclen,size_t padlen,size_t maxlen) __pure__;
 
 /* "foo" -> "foo  "
  * append padlen-srclen spaces after dest, if that is >= 0.  Truncate
  * only if total length is larger than maxlen.  Return number of
  * characters written. */
-size_t fmt_fill(char* dest,size_t srclen,size_t padlen,size_t maxlen);
+size_t fmt_fill(char* dest,size_t srclen,size_t padlen,size_t maxlen) __pure__;
 
 /* 1 -> "1", 4900 -> "4.9k", 2300000 -> "2.3M" */
-size_t fmt_human(char* dest,unsigned long long l);
+size_t fmt_human(char* dest,unsigned long long l) __pure__;
 
 /* 1 -> "1", 4900 -> "4.8k", 2300000 -> "2.2M" */
-size_t fmt_humank(char* dest,unsigned long long l);
+size_t fmt_humank(char* dest,unsigned long long l) __pure__;
 
 /* "Sun, 06 Nov 1994 08:49:37 GMT" */
-size_t fmt_httpdate(char* dest,time_t t);
+size_t fmt_httpdate(char* dest,time_t t);	/* not marked pure because it calls gmtime */
 
 /* "2014-05-27T19:22:16.247Z" */
-size_t fmt_iso8601(char* dest,time_t t);
+size_t fmt_iso8601(char* dest,time_t t) __pure__;
 
 #define FMT_UTF8 5
 #define FMT_ASN1LENGTH 17 /* enough space to hold 2^128-1 */
 #define FMT_ASN1TAG 19 /* enough space to hold 2^128-1 */
 
 /* some variable length encodings for integers */
-size_t fmt_utf8(char* dest,uint32_t n);	/* can store 0-0x7fffffff */
-size_t fmt_asn1derlength(char* dest,unsigned long long l);	/* 0-0x7f: 1 byte, above that 1+bytes_needed bytes */
-size_t fmt_asn1dertag(char* dest,unsigned long long l);	/* 1 byte for each 7 bits; upper bit = more bytes coming */
-size_t fmt_varint(char* dest,unsigned long long l);	/* protocol buffers encoding; like asn1dertag but little endian */
-size_t fmt_pb_tag(char* dest,size_t fieldno,unsigned char type);	/* protocol buffer tag */
-size_t fmt_pb_type0_int(char* dest,signed long long l);	/* protocol buffers encoding: type 0 integer */
-size_t fmt_pb_type1_double(char* dest,double d);	/* protocol buffers encoding: double (64-bit little endian blob) */
-size_t fmt_pb_type1_fixed64(char* dest,uint64_t l);	/* protocol buffers encoding: 64-bit little endian blob */
-size_t fmt_pb_type2_string(char* dest,const char* s,size_t l);	/* protocol buffers encoding: varint length + blob */
-size_t fmt_pb_type5_float(char* dest,float f);		/* protocol buffers encoding: float (32-bit little endian blob) */
-size_t fmt_pb_type5_fixed32(char* dest,uint32_t l);	/* protocol buffers encoding: 32-bit little endian blob */
-
-static inline size_t fmt_pb_int(char* dest,size_t fieldno,signed long long l) {
-  size_t n=fmt_pb_tag(dest,fieldno,0);
-  return n+fmt_pb_type0_int(dest?dest+n:0,l);
-}
-
-static inline size_t fmt_pb_double(char* dest,size_t fieldno,double d) {
-  size_t n=fmt_pb_tag(dest,fieldno,1);
-  return n+fmt_pb_type1_double(dest?dest+n:0,d);
-}
-
-static inline size_t fmt_pb_float(char* dest,size_t fieldno,float f) {
-  size_t n=fmt_pb_tag(dest,fieldno,5);
-  return n+fmt_pb_type5_float(dest?dest+n:0,f);
-}
-
-static inline size_t fmt_pb_string(char* dest,size_t fieldno,const char* s,size_t l) {
-  size_t n=fmt_pb_tag(dest,fieldno,2);
-  size_t m;
-  if (add_of(m,fmt_pb_type2_string(NULL,s,l),n)) return 0;
-  return n+fmt_pb_type2_string(dest?dest+n:0,s,l);
-}
-
-size_t fmt_netstring(char* dest,const char* src,size_t len);
+size_t fmt_utf8(char* dest,uint32_t n) __pure__;	/* can store 0-0x7fffffff */
+size_t fmt_asn1derlength(char* dest,unsigned long long l) __pure__;	/* 0-0x7f: 1 byte, above that 1+bytes_needed bytes */
+size_t fmt_asn1dertag(char* dest,unsigned long long l) __pure__;	/* 1 byte for each 7 bits; upper bit = more bytes coming */
+
+/* Google Protocol Buffers, https://developers.google.com/protocol-buffers/docs/encoding */
+size_t fmt_varint(char* dest,unsigned long long l) __pure__;	/* protocol buffers encoding; like asn1dertag but little endian */
+size_t fmt_pb_tag(char* dest,size_t fieldno,unsigned char type) __pure__;	/* protocol buffer tag */
+size_t fmt_pb_type0_int(char* dest,unsigned long long l) __pure__;	/* protocol buffers encoding: type 0 bool/enum/int32/uint32/int64/uint64 */
+size_t fmt_pb_type0_sint(char* dest,signed long long l) __pure__;/* protocol buffers encoding: type 0 sint32/sint64 */
+size_t fmt_pb_type1_double(char* dest,double d) __pure__;	/* protocol buffers encoding: double (64-bit little endian blob) */
+size_t fmt_pb_type1_fixed64(char* dest,uint64_t l) __pure__;	/* protocol buffers encoding: 64-bit little endian blob */
+
+/* fmt_pb_type2_string can return 0 if (s,l) is clearly invalid */
+size_t fmt_pb_type2_string(char* dest,const char* s,size_t l) __pure__;	/* protocol buffers encoding: varint length + blob */
+size_t fmt_pb_type5_float(char* dest,float f) __pure__;		/* protocol buffers encoding: float (32-bit little endian blob) */
+size_t fmt_pb_type5_fixed32(char* dest,uint32_t l) __pure__;	/* protocol buffers encoding: 32-bit little endian blob */
+
+size_t fmt_pb_int(char* dest,size_t fieldno,unsigned long long l) __pure__;
+size_t fmt_pb_sint(char* dest,size_t fieldno,signed long long l) __pure__;
+size_t fmt_pb_double(char* dest,size_t fieldno,double d) __pure__;
+size_t fmt_pb_float(char* dest,size_t fieldno,float f) __pure__;
+size_t fmt_pb_string(char* dest,size_t fieldno,const char* s,size_t l) __pure__;
+
+/* fmt_netstring can return 0 if (src,len) is clearly invalid */
+size_t fmt_netstring(char* dest,const char* src,size_t len) __pure__;
 
 /* Marshaling helper functions.
  * Escape one character, no matter if it needs escaping or not.
@@ -193,27 +185,27 @@ size_t fmt_netstring(char* dest,const char* src,size_t len);
  * unicode codepoint) may be limited to 0x7f, 0xff or 0x10ffff. */
 
 /* XML escaping: '&' -> '&amp;', '<' -> '&lt;', 'ö' -> '&#xf6;' */
-size_t fmt_escapecharxml(char* dest,uint32_t ch);
+size_t fmt_escapecharxml(char* dest,uint32_t ch) __pure__;
 /* HTML escaping is the same as XML escaping. */
-size_t fmt_escapecharhtml(char* dest,uint32_t ch);
+size_t fmt_escapecharhtml(char* dest,uint32_t ch) __pure__;
 
 /* JSON escaping: '\' -> '\\', '"' -> '\"', 'ö' -> '\u00f6' */
-size_t fmt_escapecharjson(char* dest,uint32_t ch);
+size_t fmt_escapecharjson(char* dest,uint32_t ch) __pure__;
 
 /* MIME quoted-printable escaping: 'ö' -> '=f6', characters > 0xff not supported */
-size_t fmt_escapecharquotedprintable(char* dest,uint32_t ch);
+size_t fmt_escapecharquotedprintable(char* dest,uint32_t ch) __pure__;
 
 /* MIME quoted-printable escaping with UTF-8: 'ö' -> '=c3=b6', characters > 0x7fffffff not supported */
-size_t fmt_escapecharquotedprintableutf8(char* dest,uint32_t ch);
+size_t fmt_escapecharquotedprintableutf8(char* dest,uint32_t ch) __pure__;
 
 /* C escaping: '\' -> '\\', newline -> '\n', 0xc2 -> '\302' */
-size_t fmt_escapecharc(char* dest,uint32_t ch);
+size_t fmt_escapecharc(char* dest,uint32_t ch) __pure__;
 
 /* internal functions, may be independently useful */
-char fmt_tohex(char c);
+char fmt_tohex(char c) __attribute__((__const__));
 
 #define fmt_strm(b,...) fmt_strm_internal(b,__VA_ARGS__,(char*)0)
-size_t fmt_strm_internal(char* dest,...);
+size_t fmt_strm_internal(char* dest,...) __pure__;
 
 #ifndef MAX_ALLOCA
 #define MAX_ALLOCA 100000
diff --git a/fmt/fmt_pb_double.c b/fmt/fmt_pb_double.c
new file mode 100644
index 0000000..50969a2
--- /dev/null
+++ b/fmt/fmt_pb_double.c
@@ -0,0 +1,7 @@
+#include "fmt.h"
+
+size_t fmt_pb_double(char* dest,size_t fieldno,double d) {
+  size_t n=fmt_pb_tag(dest,fieldno,1);
+  return n+fmt_pb_type1_double(dest?dest+n:0,d);
+}
+
diff --git a/fmt/fmt_pb_float.c b/fmt/fmt_pb_float.c
new file mode 100644
index 0000000..0812313
--- /dev/null
+++ b/fmt/fmt_pb_float.c
@@ -0,0 +1,6 @@
+#include "fmt.h"
+
+size_t fmt_pb_float(char* dest,size_t fieldno,float f) {
+  size_t n=fmt_pb_tag(dest,fieldno,5);
+  return n+fmt_pb_type5_float(dest?dest+n:0,f);
+}
diff --git a/fmt/fmt_pb_int.c b/fmt/fmt_pb_int.c
new file mode 100644
index 0000000..76296ab
--- /dev/null
+++ b/fmt/fmt_pb_int.c
@@ -0,0 +1,7 @@
+#include "fmt.h"
+
+size_t fmt_pb_int(char* dest,size_t fieldno,unsigned long long l) {
+  size_t n=fmt_pb_tag(dest,fieldno,0);
+  return n+fmt_pb_type0_int(dest?dest+n:0,l);
+}
+
diff --git a/fmt/fmt_pb_sint.c b/fmt/fmt_pb_sint.c
new file mode 100644
index 0000000..2cb13bd
--- /dev/null
+++ b/fmt/fmt_pb_sint.c
@@ -0,0 +1,6 @@
+#include "fmt.h"
+
+size_t fmt_pb_sint(char* dest,size_t fieldno,signed long long l) {
+  size_t n=fmt_pb_tag(dest,fieldno,0);
+  return n+fmt_pb_type0_sint(dest?dest+n:0,l);
+}
diff --git a/fmt/fmt_pb_string.c b/fmt/fmt_pb_string.c
new file mode 100644
index 0000000..4bcb066
--- /dev/null
+++ b/fmt/fmt_pb_string.c
@@ -0,0 +1,9 @@
+#include "fmt.h"
+#include "rangecheck.h"
+
+size_t fmt_pb_string(char* dest,size_t fieldno,const char* s,size_t l) {
+  size_t n=fmt_pb_tag(dest,fieldno,2);
+  size_t m;
+  if (add_of(m,fmt_pb_type2_string(NULL,s,l),n)) return 0;
+  return n+fmt_pb_type2_string(dest?dest+n:0,s,l);
+}
diff --git a/fmt/fmt_pb_tag.c b/fmt/fmt_pb_tag.c
new file mode 100644
index 0000000..4b39bba
--- /dev/null
+++ b/fmt/fmt_pb_tag.c
@@ -0,0 +1,6 @@
+#include "fmt.h"
+
+size_t fmt_pb_tag(char* dest,size_t fieldno,unsigned char type) {
+  if (type>5 || (fieldno >> (sizeof(fieldno)*8-3))) return 0;
+  return fmt_varint(dest,(type&7) | (fieldno<<3));
+}
diff --git a/fmt/fmt_pb_type0_sint.c b/fmt/fmt_pb_type0_sint.c
new file mode 100644
index 0000000..41353c0
--- /dev/null
+++ b/fmt/fmt_pb_type0_sint.c
@@ -0,0 +1,5 @@
+#include "fmt.h"
+
+size_t fmt_pb_type0_sint(char* dest,signed long long l) {
+  return fmt_varint(dest,(l << 1) ^ (l >> (sizeof(l)*8-1)));
+}
diff --git a/fmt/fmt_pb_type1_double.c b/fmt/fmt_pb_type1_double.c
new file mode 100644
index 0000000..f29b259
--- /dev/null
+++ b/fmt/fmt_pb_type1_double.c
@@ -0,0 +1,12 @@
+#include "fmt.h"
+#include "compiletimeassert.h"
+
+size_t fmt_pb_type1_double(char* dest,double d) {
+  union {
+    double d;
+    uint64_t u;
+  } u;
+  compiletimeassert(sizeof(double) == 8);
+  u.d=d;
+  return fmt_pb_type1_fixed64(dest,u.u);
+}
diff --git a/fmt/fmt_pb_type1_fixed64.c b/fmt/fmt_pb_type1_fixed64.c
new file mode 100644
index 0000000..67aaf36
--- /dev/null
+++ b/fmt/fmt_pb_type1_fixed64.c
@@ -0,0 +1,7 @@
+#include "fmt.h"
+#include "uint64.h"
+
+size_t fmt_pb_type1_fixed64(char* dest,uint64_t l) {
+  if (dest) uint64_pack(dest,l);
+  return 8;
+}
diff --git a/fmt/fmt_pb_type2_string.c b/fmt/fmt_pb_type2_string.c
new file mode 100644
index 0000000..aa6b516
--- /dev/null
+++ b/fmt/fmt_pb_type2_string.c
@@ -0,0 +1,10 @@
+#include "fmt.h"
+#include "rangecheck.h"
+#include <string.h>
+
+size_t fmt_pb_type2_string(char* dest,const char* s,size_t l) {
+  size_t n=fmt_varint(dest,l);
+  if (add_of(n,l,n)) return 0;
+  if (dest) memcpy(dest+n-l,s,l);
+  return n;
+}
diff --git a/fmt/fmt_pb_type5_fixed32.c b/fmt/fmt_pb_type5_fixed32.c
new file mode 100644
index 0000000..70d7c5b
--- /dev/null
+++ b/fmt/fmt_pb_type5_fixed32.c
@@ -0,0 +1,7 @@
+#include "fmt.h"
+#include "uint32.h"
+
+size_t fmt_pb_type5_fixed32(char* dest,uint32_t l) {
+  if (dest) uint32_pack(dest,l);
+  return 4;
+}
diff --git a/fmt/fmt_pb_type5_float.c b/fmt/fmt_pb_type5_float.c
new file mode 100644
index 0000000..408bfd2
--- /dev/null
+++ b/fmt/fmt_pb_type5_float.c
@@ -0,0 +1,12 @@
+#include "fmt.h"
+#include "compiletimeassert.h"
+
+size_t fmt_pb_type5_float(char* dest,float f) {
+  union {
+    float f;
+    uint32_t u;
+  } u;
+  compiletimeassert(sizeof(float) == 4);
+  u.f=f;
+  return fmt_pb_type5_fixed32(dest,u.u);
+}
diff --git a/fmt/fmt_varint.c b/fmt/fmt_varint.c
new file mode 100644
index 0000000..ae64b29
--- /dev/null
+++ b/fmt/fmt_varint.c
@@ -0,0 +1,14 @@
+#include "fmt.h"
+
+/* write int in least amount of bytes, return number of bytes */
+/* as used in varints from Google protocol buffers */
+size_t fmt_varint(char* dest,unsigned long long l) {
+  /* high bit says if more bytes are coming, lower 7 bits are payload; little endian */
+  size_t i;
+  for (i=0; l; ++i, l>>=7) {
+    if (dest) dest[i]=(l&0x7f) | ((!!(l&~0x7f))<<7);
+  }
+  return i;
+}
+
+size_t fmt_pb_type0_int(char* dest,unsigned long long l) __attribute__((alias("fmt_varint")));
diff --git a/scan.h b/scan.h
index f366178..13becb9 100644
--- a/scan.h
+++ b/scan.h
@@ -114,6 +114,36 @@ size_t scan_utf8(const char* in,size_t len,uint32_t* n) __pure__;
 size_t scan_asn1derlength(const char* in,size_t len,unsigned long long* n) __pure__;
 size_t scan_asn1dertag(const char* in,size_t len,unsigned long long* n) __pure__;
 
+/* Google protocol buffers */
+/* A protocol buffer is a sequence of (tag,value).
+ * Parse each tag with scan_pb_tag, then look at the field number to see
+ *   which field in your struct is being sent. Integers must have type
+ *   0, double type 1, strings type 2 and floats type 5. However, you
+ *   have to check this yourself.
+ */ 
+size_t scan_varint(const char* in,size_t len, unsigned long long* n) __pure__;	/* internal */
+size_t scan_pb_tag(const char* in,size_t len, size_t* fieldno,unsigned char* type) __pure__;
+
+/* Then, depending on the field number, validate the type and call the
+ * corresponding of these functions to parse the value */
+size_t scan_pb_type0_int(const char* in,size_t len,unsigned long long* l) __pure__;
+size_t scan_pb_type0_sint(const char* in,size_t len,signed long long* l) __pure__;
+size_t scan_pb_type1_double(const char* in,size_t len,double* d) __pure__;
+size_t scan_pb_type1_fixed64(const char* in,size_t len,uint64_t* b) __pure__;
+/* NOTE: scan_pb_type2_stringlen only parses the length of the string,
+ * not the string itself. It will return the number of bytes parsed in
+ * the length, then set slen to the value of the length integer it just
+ * read, and let string point to the next byte (where the actual string
+ * starts). To advance in the protocol buffer, you'll have to skip the
+ * return value of this function + slen bytes.
+ * This is done so you can detect too large strings and abort the
+ * parsing early without having to read and allocate memory for the rest
+ * (potentially gigabytes) of the data announced by one unreasonable
+ * string length value. */
+size_t scan_pb_type2_stringlen(const char* in,size_t len,const char** string, size_t* slen) __pure__;
+size_t scan_pb_type5_float(const char* in,size_t len,float* f) __pure__;
+size_t scan_pb_type5_fixed32(const char* in,size_t len,uint32_t* b) __pure__;
+
 /* parse a netstring, input buffer is in (len bytes).
  * if parsing is successful:
  *   *dest points to string and *slen is size of string
diff --git a/scan/scan_pb_tag.c b/scan/scan_pb_tag.c
new file mode 100644
index 0000000..d4b4f5e
--- /dev/null
+++ b/scan/scan_pb_tag.c
@@ -0,0 +1,10 @@
+#include "scan.h"
+
+size_t scan_pb_tag(const char* in,size_t len, size_t* fieldno,unsigned char* type) {
+  unsigned long long l;
+  size_t n=scan_varint(in,len,&l);
+  if (n==0) return 0;
+  *type=l&7;
+  *fieldno=(l>>3);
+  return n;
+}
diff --git a/scan/scan_pb_type0_sint.c b/scan/scan_pb_type0_sint.c
new file mode 100644
index 0000000..07fe9f1
--- /dev/null
+++ b/scan/scan_pb_type0_sint.c
@@ -0,0 +1,9 @@
+#include "scan.h"
+
+size_t scan_pb_type0_sint(const char* in,size_t len,signed long long* l) {
+  unsigned long long m;
+  size_t n=scan_varint(in,len,&m);
+  if (!n) return 0;
+  *l=(-(m&1)) ^ (m>>1);
+  return n;
+}
diff --git a/scan/scan_pb_type1_double.c b/scan/scan_pb_type1_double.c
new file mode 100644
index 0000000..2740f24
--- /dev/null
+++ b/scan/scan_pb_type1_double.c
@@ -0,0 +1,13 @@
+#include "scan.h"
+#include "compiletimeassert.h"
+
+size_t scan_pb_type1_double(const char* in,size_t len,double* d) {
+  union {
+    double d;
+    uint64_t u;
+  } u;
+  compiletimeassert(sizeof(double)==8);
+  size_t n=scan_pb_type1_fixed64(in,len,&u.u);
+  if (n) *d=u.d;
+  return n;
+}
diff --git a/scan/scan_pb_type1_fixed64.c b/scan/scan_pb_type1_fixed64.c
new file mode 100644
index 0000000..86fce5d
--- /dev/null
+++ b/scan/scan_pb_type1_fixed64.c
@@ -0,0 +1,8 @@
+#include "scan.h"
+#include "uint64.h"
+
+size_t scan_pb_type1_fixed64(const char* in,size_t len,uint64_t* d) {
+  if (len<8) return 0;
+  uint64_unpack(in,d);
+  return 8;
+}
diff --git a/scan/scan_pb_type2_stringlen.c b/scan/scan_pb_type2_stringlen.c
new file mode 100644
index 0000000..9224f55
--- /dev/null
+++ b/scan/scan_pb_type2_stringlen.c
@@ -0,0 +1,11 @@
+#include "scan.h"
+#include "rangecheck.h"
+
+size_t scan_pb_type2_stringlen(const char* in,size_t len,const char** string, size_t* slen) {
+  unsigned long long l;
+  size_t n=scan_varint(in,len,&l);
+  if (n && !assign(*slen,l)) {
+    *string=in+n;
+  }
+  return n;
+}
diff --git a/scan/scan_pb_type5_fixed32.c b/scan/scan_pb_type5_fixed32.c
new file mode 100644
index 0000000..9516311
--- /dev/null
+++ b/scan/scan_pb_type5_fixed32.c
@@ -0,0 +1,8 @@
+#include "scan.h"
+#include "uint32.h"
+
+size_t scan_pb_type5_fixed32(const char* in,size_t len,uint32_t* d) {
+  if (len<4) return 0;
+  uint32_unpack(in,d);
+  return 4;
+}
diff --git a/scan/scan_pb_type5_float.c b/scan/scan_pb_type5_float.c
new file mode 100644
index 0000000..7630423
--- /dev/null
+++ b/scan/scan_pb_type5_float.c
@@ -0,0 +1,13 @@
+#include "scan.h"
+#include "compiletimeassert.h"
+
+size_t scan_pb_type5_float(const char* in,size_t len,float* f) {
+  union {
+    float f;
+    uint32_t u;
+  } u;
+  compiletimeassert(sizeof(float)==4);
+  size_t n=scan_pb_type5_fixed32(in,len,&u.u);
+  if (n) *f=u.f;
+  return n;
+}
diff --git a/scan/scan_varint.c b/scan/scan_varint.c
new file mode 100644
index 0000000..8c6a7ff
--- /dev/null
+++ b/scan/scan_varint.c
@@ -0,0 +1,18 @@
+#include "scan.h"
+
+size_t scan_varint(const char* in,size_t len, unsigned long long* n) {
+  size_t i;
+  unsigned long long l;
+  if (len==0) return 0;
+  l=0;
+  for (l=0, i=0; i<len; ++i) {
+    l+=(in[i]&0x7f) << (i*7);
+    if (!(in[i]&0x80)) {
+      *n=l;
+      return i+1;
+    }
+  }
+  return 0;
+}
+
+size_t scan_pb_type0_int(const char* dest,size_t len,unsigned long long* l) __attribute__((alias("scan_varint")));
diff --git a/t.c b/t.c
index 57d7ede..a170826 100644
--- a/t.c
+++ b/t.c
@@ -68,6 +68,19 @@ static int ret1(const char* s,void* foo) {
 }
 
 int main(int argc,char* argv[]) {
+  char buf[100];
+  assert(fmt_varint(buf,1)==1 && buf[0]==1);
+  fmt_varint(buf,300);
+  assert(fmt_varint(buf,300)==2 && buf[0]==(char)0xac && buf[1]==0x02);
+#if 0
+  const char buf[]="fnord\n";
+  buffer_puts(buffer_1,buf);
+  strcpy((char*)buf,"foo\n");
+  buffer_puts(buffer_1,buf);
+  buffer_puts(buffer_1,"bar\n");
+  buffer_flush(buffer_1);
+#endif
+#if 0
   static critbit0_tree t;
   assert(critbit0_insert(&t,"fnord")==2);
   assert(critbit0_insert(&t,"fnord2")==2);
@@ -78,6 +91,7 @@ int main(int argc,char* argv[]) {
   assert(critbit0_allprefixed(&t,"fnord",ret0,NULL)==0);
   assert(critbit0_delete(&t,"fnord2")==1);
   assert(critbit0_delete(&t,"foo")==0);
+#endif
 #if 0
   int s = socket_tcp6();
 #endif
diff --git a/test/protobuf.c b/test/protobuf.c
new file mode 100644
index 0000000..96da1d1
--- /dev/null
+++ b/test/protobuf.c
@@ -0,0 +1,50 @@
+#include "fmt.h"
+#include "scan.h"
+#include <math.h>
+#include <string.h>
+#include <assert.h>
+#include <stdio.h>
+
+int main() {
+  char buf[100];
+  double pi=M_PI;
+  float fpi=pi;
+
+  unsigned long long l;
+  size_t len;
+  unsigned char c;
+
+  assert(fmt_varint(buf,23)==1 && buf[0]==23);
+  assert(scan_varint(buf,1,&l)==1 && l==23);
+  assert(fmt_varint(buf,150)==2 && buf[0]==(char)0x96 && buf[1]==1);
+  assert(scan_varint(buf,2,&l)==2 && l==150);
+
+  assert(fmt_pb_tag(buf,23,2)==2 && (unsigned char)buf[0]==((23<<3)+2));
+  assert(scan_pb_tag(buf,2,&len,&c)==2 && len==23 && c==2);
+
+  assert(fmt_pb_type0_int(buf,150)==2 && scan_pb_type0_int(buf,2,&l)==2 && l==150);
+  assert(fmt_pb_type0_sint(buf,150)==2 && scan_pb_type0_sint(buf,2,&l)==2 && l==150);
+
+  {
+    double d;
+    assert(fmt_pb_type1_double(buf,pi)==8 && scan_pb_type1_double(buf,8,&d)==8 && d==pi);
+  }
+
+  {
+    float f;
+    assert(fmt_pb_type5_float(buf,fpi)==4 && scan_pb_type5_float(buf,4,&f)==4 && f==fpi);
+  }
+
+  {
+    const char* s;
+    size_t l;
+    assert(fmt_pb_type2_string(buf,"fnord",5)==6);
+    assert(scan_pb_type2_stringlen(buf,6,&s,&l)==1 && l==5);
+  }
+
+  assert(fmt_pb_int(buf,1,150)==3 && !memcmp(buf,"\x08\x96\x01",3));
+  assert(fmt_pb_sint(buf,2,150)==3 && !memcmp(buf,"\x10\xac\x02",3));
+  assert(fmt_pb_double(buf,3,pi)==9 && buf[0]==0x19);
+  assert(fmt_pb_float(buf,4,fpi)==5 && buf[0]==0x25);
+  assert(fmt_pb_string(buf,5,"fnord",5)==7 && !memcmp(buf,"\x2a\x05""fnord",7));
+}