semihosting: Expand qemu_semihosting_console_inc to read

Allow more than one character to be read at one time.
Will be used by m68k and nios2 semihosting for stdio.

Reviewed-by: Luc Michel <lmichel@kalray.eu>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

include/semihosting/console.h

@@ -38,19 +38,21 @@ int qemu_semihosting_console_outs(CPUArchState *env, target_ulong s);
 void qemu_semihosting_console_outc(CPUArchState *env, target_ulong c);
 
 /**
- * qemu_semihosting_console_inc:
+ * qemu_semihosting_console_read:
  * @cs: CPUState
+ * @buf: host buffer
+ * @len: buffer size
  *
- * Receive single character from debug console.  As this call may block
- * if no data is available we suspend the CPU and will re-execute the
+ * Receive at least one character from debug console.  As this call may
+ * block if no data is available we suspend the CPU and will re-execute the
  * instruction when data is there. Therefore two conditions must be met:
  *
  *   - CPUState is synchronized before calling this function
  *   - pc is only updated once the character is successfully returned
  *
- * Returns: character read OR cpu_loop_exit!
+ * Returns: number of characters read, OR cpu_loop_exit!
  */
-target_ulong qemu_semihosting_console_inc(CPUState *cs);
+int qemu_semihosting_console_read(CPUState *cs, void *buf, int len);
 
 /**
  * qemu_semihosting_log_out:

linux-user/semihost.c

@@ -56,21 +56,23 @@ void qemu_semihosting_console_outc(CPUArchState *env, target_ulong addr)
  * program is expecting more normal behaviour. This is slow but
  * nothing using semihosting console reading is expecting to be fast.
  */
-target_ulong qemu_semihosting_console_inc(CPUState *cs)
+int qemu_semihosting_console_read(CPUState *cs, void *buf, int len)
 {
-    uint8_t c;
+    int ret;
     struct termios old_tio, new_tio;
 
     /* Disable line-buffering and echo */
     tcgetattr(STDIN_FILENO, &old_tio);
     new_tio = old_tio;
     new_tio.c_lflag &= (~ICANON & ~ECHO);
+    new_tio.c_cc[VMIN] = 1;
+    new_tio.c_cc[VTIME] = 0;
     tcsetattr(STDIN_FILENO, TCSANOW, &new_tio);
 
-    c = getchar();
+    ret = fread(buf, 1, len, stdin);
 
     /* restore config */
     tcsetattr(STDIN_FILENO, TCSANOW, &old_tio);
 
-    return (target_ulong) c;
+    return ret;
 }

semihosting/arm-compat-semi.c

@@ -428,8 +428,15 @@ void do_common_semihosting(CPUState *cs)
         break;
 
     case TARGET_SYS_READC:
-        ret = qemu_semihosting_console_inc(cs);
-        common_semi_set_ret(cs, ret);
+        {
+            uint8_t ch;
+            int ret = qemu_semihosting_console_read(cs, &ch, 1);
+            if (ret == 1) {
+                common_semi_cb(cs, ch, 0);
+            } else {
+                common_semi_cb(cs, -1, EIO);
+            }
+        }
         break;
 
     case TARGET_SYS_ISERROR:

semihosting/console.c

@@ -144,12 +144,14 @@ static void console_read(void *opaque, const uint8_t *buf, int size)
     c->sleeping_cpus = NULL;
 }
 
-target_ulong qemu_semihosting_console_inc(CPUState *cs)
+int qemu_semihosting_console_read(CPUState *cs, void *buf, int len)
 {
-    uint8_t ch;
     SemihostingConsole *c = &console;
+    int ret = 0;
 
     g_assert(qemu_mutex_iothread_locked());
+
+    /* Block if the fifo is completely empty. */
     if (fifo8_is_empty(&c->fifo)) {
         c->sleeping_cpus = g_slist_prepend(c->sleeping_cpus, cs);
         cs->halted = 1;
@@ -157,8 +159,14 @@ target_ulong qemu_semihosting_console_inc(CPUState *cs)
         cpu_loop_exit(cs);
         /* never returns */
     }
-    ch = fifo8_pop(&c->fifo);
-    return (target_ulong) ch;
+
+    /* Read until buffer full or fifo exhausted. */
+    do {
+        *(char *)(buf + ret) = fifo8_pop(&c->fifo);
+        ret++;
+    } while (ret < len && !fifo8_is_empty(&c->fifo));
+
+    return ret;
 }
 
 void qemu_semihosting_console_init(void)