Initial work on GDB remote debugging support

1 files changed, 123 insertions, 0 deletions

diff --git a/gdb_remote.c b/gdb_remote.c
new file mode 100644
index 0000000..888bbb8
--- /dev/null
+++ b/gdb_remote.c
@@ -0,0 +1,123 @@
+#include "blastem.h"
+#include <unistd.h>
+#include <fcntl.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <stdio.h>
+
+#define INITIAL_BUFFER_SIZE 4096
+
+char * buf = NULL;
+char * curbuf = NULL;
+size_t bufsize;
+int cont = 0;
+int expect_break_response=0;
+uint32_t resume_pc;
+
+void gdb_debug_enter(genesis_context * gen, uint32_t pc)
+{
+	resume_pc = pc;
+	while(!cont)
+	{
+	}
+	cont = 0;
+}
+
+void gdb_run_command(genesis_context * gen, char * command)
+{
+	switch(*command)
+	{
+	case 'c':
+		if (*(command+1) != 0) {
+			resume_pc =
+		}
+		cont = 1;
+		expect_break_response = 1;
+		break;
+	case 's':
+
+	}
+}
+
+void gdb_run_commands(genesis_context * gen)
+{
+	int enter_debugger = 0;
+	char * cur = buf;
+	while(cur < curbuf);
+	{
+		if(*cur == '$') {
+			cur++
+			char * start = cur;
+			while (cur < curbuf && *cur != '#') {
+				cur++;
+			}
+			if (*cur == '#') {
+				//check to make sure we've received the checksum bytes
+				if (curbuf-cur >= 2) {
+					//TODO: verify checksum
+					//Null terminate payload
+					//send acknowledgement
+					write(FILENO_STDOUT, "+", 1);
+					gdb_run_command(genesis_context * gen, start);
+					cur += 2;
+				} else {
+					cur = start - 1;
+					break;
+				}
+			} else {
+				cur = start - 1;
+				break;
+			}
+		} else {
+			if (*cur == 0x03) {
+				enter_debugger = 1;
+			}
+			cur++;
+		}
+	}
+
+	//FIXME
+	if (consumed == curbuf-buf) {
+		curbuf = buf;
+	} else if (consumed > 0) {
+		memmove(buf, buf + consumed, curbuf - buf - consumed);
+		curbuf -= consumed;
+	}
+}
+
+void gdb_command_poll(genesis_context * gen)
+{
+	for(;;)
+	{
+		if (curbuf == buf + bufsize) {
+			//buffer is full, expand it
+			bufsize *= 2;
+			buf = realloc(buf, bufsize);
+			if (!buf) {
+				fprintf(stderr, "Failed to grow GDB command buffer to %d bytes\n", (int)bufsize);
+				exit(1);
+			}
+			curbuf = buf + bufsize/2;
+		}
+		int numread = read(STDIN_FILENO, buf, bufsize - (curbuf-buf));
+		if (numread < 0) {
+			if (errno == EAGAIN || errno == EWOULDBLOCK) {
+				return;
+			} else {
+				fprintf(stderr, "Error %d while reading GDB commands from stdin", errno);
+				exit(1);
+			}
+		} else if (numread == 0) {
+			exit(0);
+		}
+		gdb_run_commands(genesis_context * gen);
+	}
+}
+
+void gdb_remote_init()
+{
+	fcntl(STDIN_FILENO, FD_SETFL, O_NONBLOCK);
+	buf = malloc(INITIAL_BUFFER_SIZE);
+	curbuf = buf;
+	bufzie = INITIAL_BUFFER_SIZE;
+}