Add a hacky mechanism to track new lines in terminal and trace output and insert extra new lines to keep them separate.

Author: rmn30

c_emulator/riscv_platform_impl.c

@@ -49,9 +49,15 @@ uint64_t rv_htif_tohost = UINT64_C(0x80001000);
 uint64_t rv_insns_per_tick = UINT64_C(100);
 
 int term_fd = 1; // set during startup
+extern bool have_newline;
 void plat_term_write_impl(char c)
 {
   if (write(term_fd, &c, sizeof(c)) < 0) {
     fprintf(stderr, "Unable to write to terminal!\n");
   }
+  /* Trace output always goes to stdout. If the terminal is also going to stdout
+   * we try to separate them by inserting new lines before trace output when
+   * necessary (see riscv_prelude.c). */
+  if (term_fd == 1)
+    have_newline = c == '\n';
 }

c_emulator/riscv_prelude.c

@@ -2,37 +2,57 @@
 #include "riscv_config.h"
 #include "riscv_platform_impl.h"
 
+/* Attempt to keep track of whether output is at the start of a line so that we
+ * can produce nicer output if trace output interrupts terminal output. */
+bool have_newline = true;
+
+void ensure_newline()
+{
+  if (!have_newline)
+    fputc('\n', trace_log);
+}
+
 unit print_string(sail_string prefix, sail_string msg)
 {
-  printf("%s%s\n", prefix, msg);
+  ensure_newline();
+  fprintf(trace_log, "%s%s\n", prefix, msg);
+  have_newline = true;
   return UNIT;
 }
 
 unit print_instr(sail_string s)
 {
+  ensure_newline();
   if (config_print_instr)
     fprintf(trace_log, "%s\n", s);
+  have_newline = true;
   return UNIT;
 }
 
 unit print_reg(sail_string s)
 {
+  ensure_newline();
   if (config_print_reg)
     fprintf(trace_log, "%s\n", s);
+  have_newline = true;
   return UNIT;
 }
 
 unit print_mem_access(sail_string s)
 {
+  ensure_newline();
   if (config_print_mem_access)
     fprintf(trace_log, "%s\n", s);
+  have_newline = true;
   return UNIT;
 }
 
 unit print_platform(sail_string s)
 {
+  ensure_newline();
   if (config_print_platform)
     fprintf(trace_log, "%s\n", s);
+  have_newline = true;
   return UNIT;
 }
 
@@ -59,4 +79,4 @@ bool get_config_print_platform(unit u)
 bool get_config_print_exception(unit u)
 {
   return (config_print_exception) ? true : false;
-}
+}