first C hello world!

7 files changed, 66 insertions, 45 deletions

diff --git a/05/codegen.b b/05/codegen.b
index d33eb3e..d42d097 100644
--- a/05/codegen.b
+++ b/05/codegen.b
@@ -762,7 +762,6 @@ function generate_cast_top_of_stack
 	
 	if *1to == TYPE_VOID goto gen_cast_to_void
 	if *1from == TYPE_VOID goto bad_gen_cast ; cast from void to something - that's bad
-	if *1from == TYPE_ARRAY goto bad_gen_cast ; cast array (this probably won't ever happen because of decaying)
 	if *1to == TYPE_ARRAY goto bad_gen_cast ; cast to array
 	if *1from == TYPE_FUNCTION goto bad_gen_cast ; shouldn't happen
 	if *1to == TYPE_FUNCTION goto bad_gen_cast ; shouldn't happen
@@ -793,6 +792,7 @@ function generate_cast_top_of_stack
 		emit_add_rsp_imm32(c)
 		return
 	:gen_cast_to_integer
+		if *1from == TYPE_ARRAY goto return_0 ;  e.g. (void *)"hello"
 		if *1from == *1to goto return_0 ; casting from type to same type
 		if *1from == TYPE_POINTER goto return_0 ; no need to do anything
 		; cast float/double to integer
@@ -3001,7 +3001,7 @@ function generate_code
 	
 	; program header 3 (rwdata)
 	emit_dword(1) ; loadable segment
-	emit_dword(6) ; read/write
+	emit_dword(7) ; read/write/execute  (this needs to be executable for `syscall` to be implementable)
 	emit_qword(RWDATA_ADDR) ; offset in file
 	emit_qword(RWDATA_ADDR) ; virtual address
 	emit_qword(0) ; physical address
diff --git a/05/constants.b b/05/constants.b
index 7bcc2aa..c4c4676 100644
--- a/05/constants.b
+++ b/05/constants.b
@@ -536,6 +536,9 @@
 :str_comment_end
 	string */
 	byte 0
+:str_one_line_comment
+	string //
+	byte 0
 :str_lshift_eq
 	string <<=
 	byte 0
diff --git a/05/main.c b/05/main.c
index 6c19317..fc4b036 100644
--- a/05/main.c
+++ b/05/main.c
@@ -1,49 +1,50 @@
-typedef unsigned long va_list;
-#define va_start(list, arg) ((list) = (unsigned long)&arg)
-#define va_arg(list, type) (*((type *)(list += ((sizeof(type) + 7) & 0xfffffffffffffff8))))
-#define va_end(list)
+static unsigned char __syscall_data[] = {
+	// mov rax, [rsp+24]
+	0x48, 0x8b, 0x84, 0x24, 24, 0, 0, 0,
+	// mov rdi, rax
+	0x48, 0x89, 0xc7,
+	// mov rax, [rsp+32]
+	0x48, 0x8b, 0x84, 0x24, 32, 0, 0, 0,
+	// mov rsi, rax
+	0x48, 0x89, 0xc6,
+	// mov rax, [rsp+40]
+	0x48, 0x8b, 0x84, 0x24, 40, 0, 0, 0,
+	// mov rdx, rax
+	0x48, 0x89, 0xc2,
+	// mov rax, [rsp+48]
+	0x48, 0x8b, 0x84, 0x24, 48, 0, 0, 0,
+	// mov r10, rax
+	0x49, 0x89, 0xc2,
+	// mov rax, [rsp+56]
+	0x48, 0x8b, 0x84, 0x24, 56, 0, 0, 0,
+	// mov r8, rax
+	0x49, 0x89, 0xc0,
+	// mov rax, [rsp+64]
+	0x48, 0x8b, 0x84, 0x24, 64, 0, 0, 0,
+	// mov r9, rax
+	0x49, 0x89, 0xc1,
+	// mov rax, [rsp+16]
+	0x48, 0x8b, 0x84, 0x24, 16, 0, 0, 0,
+	// syscall
+	0x0f, 0x05,
+	// mov [rsp+8], rax
+	0x48, 0x89, 0x84, 0x24, 8, 0, 0, 0,
+	// ret
+	0xc3
+};
 
-int sum(int n, ...) {
-	va_list args;
-	int i;
-	int total = 0;
-	va_start(args, n);
-	for (i = 0; i < n; ++i) {
-		total += va_arg(args, int);
-	}
-	return total;
-}
-
-long factorial(long x) {
-	if (x == 0) {
-		return 1;
-	} else {
-		return x * factorial(x-1);
-	}
-}
+#define __syscall(no, arg1, arg2, arg3, arg4, arg5, arg6)\
+	(((unsigned long (*)(unsigned long, unsigned long, unsigned long, unsigned long, unsigned long, unsigned long, unsigned long))__syscall_data)\
+		(no, arg1, arg2, arg3, arg4, arg5, arg6))
 
-long fibonacci(long x) {
-	return x > 0 ?
-		x > 1 ?
-			fibonacci(x-1) + fibonacci(x-2)
-		: 1
-		: 0;
-}
-
-long gcd(long a, long b) {
-	while (a != 0) {
-		long temp = a;
-		a = b % a;
-		b = temp;
-	}
-	return b;
-}
+typedef unsigned long size_t;
 
-int f() {
-	lb: goto lb;
+long write(int fd, void *buf, size_t count) {
+	__syscall(1, fd, buf, count, 0, 0, 0);
 }
 
-int main(int argc, char **argv) {	
-	return sum(3, -100, 200, -300);
+int main(int argc, char **argv) {
+	write(1, "Hello, world!\n", 14);
+	return 0;
 }
 
diff --git a/05/parse.b b/05/parse.b
index 52c8d4a..4373680 100644
--- a/05/parse.b
+++ b/05/parse.b
@@ -323,7 +323,9 @@ function parse_toplevel_declaration
 		
 		ident_list_add(functions_required_stack_space, f_name, curr_function_stack_space)
 		
-		;print_statement(out0)
+		; ENABLE/DISABLE PARSING DEBUG OUTPUT:
+		print_statement(out0)
+		
 		goto parse_tld_ret
 		
 		:function_no_param_name
diff --git a/05/preprocess.b b/05/preprocess.b
index 9a7dd5c..2a94119 100644
--- a/05/preprocess.b
+++ b/05/preprocess.b
@@ -88,6 +88,8 @@ function split_into_preprocessing_tokens
 		if b != 0 goto pptoken_number
 		b = isalpha_or_underscore(c)
 		if b != 0 goto pptoken_identifier
+		b = str_startswith(in, .str_one_line_comment)
+		if b != 0 goto pptoken_one_line_comment
 		b = str_startswith(in, .str_comment_start)
 		if b != 0 goto pptoken_comment
 		; now we check for all the various operators and symbols in C
@@ -169,6 +171,10 @@ function split_into_preprocessing_tokens
 		; " each non-white-space character that cannot be one of the above"
 		goto pptoken_single_character
 		
+		:pptoken_one_line_comment
+			; skip over comment
+			in = memchr(in, 10)
+			goto pptokens_loop
 		:pptoken_comment
 			; emit a space ("Each comment is replaced by one space character.")
 			*1out = 32
diff --git a/05/stdarg.h b/05/stdarg.h
new file mode 100644
index 0000000..68fcd8e
--- /dev/null
+++ b/05/stdarg.h
@@ -0,0 +1,4 @@
+typedef unsigned long va_list;
+#define va_start(list, arg) ((list) = (unsigned long)&arg)
+#define va_arg(list, type) (*((type *)(list += ((sizeof(type) + 7) & 0xfffffffffffffff8))))
+#define va_end(list)
diff --git a/README.md b/README.md
index bc55a8b..ec85c7e 100644
--- a/README.md
+++ b/README.md
@@ -217,6 +217,11 @@ ax  bx  cx  dx  sp  bp  si  di
 │ syscall              │ 0f 05             │ execute a system call                  │
 │ nop                  │ 90                │ do nothing                             │
 └──────────────────────┴───────────────────┴────────────────────────────────────────┘
+
+SYSCALLS
+Arguments are passed in
+	rdi, rsi, rdx, r10, r8, r9
+The return value is placed in rax.
 ```
 
 More will be added in the future as needed.