[Qemu-devel] [PATCH v3 4/5] qtest: precompute hex nibs

[John Snow]

Instead of letting printf and friends do this for us
one byte at a time, fill a buffer ourselves and then
send the entire buffer in one go.

This gives a moderate speed improvement over the old
method.

Signed-off-by: John Snow <address@hidden>
---
 qtest.c          | 20 ++++++++++++++++----
 tests/libqtest.c | 17 ++++++++++++++---
 2 files changed, 30 insertions(+), 7 deletions(-)

diff --git a/qtest.c b/qtest.c
index c1a0493..383f9ed 100644
--- a/qtest.c
+++ b/qtest.c
@@ -157,6 +157,8 @@ static bool qtest_opened;
  * NUM=0 even though it is remapped to GSI 2).
  */
 
+static const char *hex = "0123456789abcdef";
+
 static int hex2nib(char ch)
 {
     if (ch >= '0' && ch <= '9') {
@@ -170,6 +172,12 @@ static int hex2nib(char ch)
     }
 }
 
+static inline void byte2hex(uint8_t byte, uint8_t *out)
+{
+    *out++ = hex[byte >> 4];
+    *out = hex[byte & 0x0F];
+}
+
 static void qtest_get_time(qemu_timeval *tv)
 {
     qemu_gettimeofday(tv);
@@ -414,6 +422,7 @@ static void qtest_process_command(CharDriverState *chr, 
gchar **words)
     } else if (strcmp(words[0], "read") == 0) {
         uint64_t addr, len, i;
         uint8_t *data;
+        uint8_t *enc;
 
         g_assert(words[1] && words[2]);
         addr = strtoull(words[1], NULL, 0);
@@ -422,14 +431,17 @@ static void qtest_process_command(CharDriverState *chr, 
gchar **words)
         data = g_malloc(len);
         cpu_physical_memory_read(addr, data, len);
 
-        qtest_send_prefix(chr);
-        qtest_send(chr, "OK 0x");
+        enc = g_malloc(2 * len + 1);
         for (i = 0; i < len; i++) {
-            qtest_sendf(chr, "%02x", data[i]);
+            byte2hex(data[i], &enc[i * 2]);
         }
-        qtest_send(chr, "\n");
+        enc[2 * len] = '\0';
+
+        qtest_send_prefix(chr);
+        qtest_sendf(chr, "OK 0x%s\n", enc);
 
         g_free(data);
+        g_free(enc);
     } else if (strcmp(words[0], "b64read") == 0) {
         uint64_t addr, len;
         uint8_t *data;
diff --git a/tests/libqtest.c b/tests/libqtest.c
index 055aad6..1b246c9 100644
--- a/tests/libqtest.c
+++ b/tests/libqtest.c
@@ -651,6 +651,8 @@ uint64_t qtest_readq(QTestState *s, uint64_t addr)
     return qtest_read(s, "readq", addr);
 }
 
+static const char *hex = "0123456789abcdef";
+
 static int hex2nib(char ch)
 {
     if (ch >= '0' && ch <= '9') {
@@ -664,6 +666,12 @@ static int hex2nib(char ch)
     }
 }
 
+static inline void byte2hex(uint8_t byte, uint8_t *out)
+{
+    *out++ = hex[byte >> 4];
+    *out = hex[byte & 0x0f];
+}
+
 void qtest_memread(QTestState *s, uint64_t addr, void *data, size_t size)
 {
     uint8_t *ptr = data;
@@ -730,13 +738,16 @@ void qtest_memwrite(QTestState *s, uint64_t addr, const 
void *data, size_t size)
 {
     const uint8_t *ptr = data;
     size_t i;
+    uint8_t *enc = g_malloc(2 * size + 1);
 
-    qtest_sendf(s, "write 0x%" PRIx64 " 0x%zx 0x", addr, size);
     for (i = 0; i < size; i++) {
-        qtest_sendf(s, "%02x", ptr[i]);
+        byte2hex(ptr[i], &enc[i * 2]);
     }
-    qtest_sendf(s, "\n");
+    enc[2 * size] = '\0';
+
+    qtest_sendf(s, "write 0x%" PRIx64 " 0x%zx 0x%s\n", addr, size, enc);
     qtest_rsp(s, 0);
+    g_free(enc);
 }
 
 void qtest_memset(QTestState *s, uint64_t addr, uint8_t pattern, size_t size)
-- 
2.1.0