From 90689d22cccce853ab6cb7dd078baaa501afb777 Mon Sep 17 00:00:00 2001
From: Andreas Baumann <mail@andreasbaumann.cc>
Date: Sun, 26 Sep 2021 20:31:51 +0200
Subject: cc: - fixed zeroing of EDX before division if operating register was
 EAX - implemented simple itoa in assembly in putint operation

---
 miniany/README  |   4 +++
 miniany/cc.c    | 101 +++++++++++++++++++++++++++++++++++++++++++-------------
 miniany/test1.c |   3 +-
 3 files changed, 84 insertions(+), 24 deletions(-)

diff --git a/miniany/README b/miniany/README
index 033f3d4..6367011 100644
--- a/miniany/README
+++ b/miniany/README
@@ -73,6 +73,10 @@ complex things into our own compiler.
 * https://github.com/lotabout/write-a-C-interpreter/blob/master/tutorial/en/: tutorial
   based on C4 how to build a C interpreter, explains nicely details in C4.
 
+* https://github.com/felipensp/assembly/blob/master/x86/itoa.s,
+  https://baptiste-wicht.com/posts/2011/11/print-strings-integers-intel-assembly.html,
+  putint for early debugging
+
 * documentation
   * "Compiler Construction", Niklaus Wirth
   * https://github.com/DoctorWkt/acwj: a nice series on building a C compiler,
diff --git a/miniany/cc.c b/miniany/cc.c
index b9cfe5a..acba6df 100644
--- a/miniany/cc.c
+++ b/miniany/cc.c
@@ -702,6 +702,11 @@ int genDiv( struct Generator *generator, int leftreg, int rightreg )
 	int reg;
 	
 	if( leftreg == EAX ) {
+		if( !generator->regFree[EDX] ) {
+			genSaveReg( generator, EDX );
+		}
+		putstring( "mov edx, 0" );
+		putnl( );
 		reg = genBinary( "div", generator, leftreg, rightreg, 1 );
 	} else {
 		if( !generator->regFree[EAX] ) {
@@ -795,34 +800,85 @@ void genPrologue( struct Compiler *compiler )
 	putstring( "format binary" ); putnl( );
 	putstring( "use32" ); putnl( );
 	putstring( "org $1000000" ); putnl( );
-	putstring( "jmp _start" ); putnl( );
+	putstring( "jmp _start" ); putnl( );	
 	putstring( "putint:" ); putnl( );
+	putstring( "mov esi, 0xa" ); putnl( );
+	putstring( "lea edi, [putint_string_fmt]" ); putnl( );
+	putstring( "add edi, 9" ); putnl( );
+	putstring( "itoa_loop:" ); putnl( );
+	putstring( "mov edx, 0" ); putnl( );
+	putstring( "div esi" ); putnl( );
+	putstring( "add edx, 0x30" ); putnl( );
+	putstring( "mov byte [edi], dl" ); putnl( );
+	putstring( "dec edi" ); putnl( );
+	putstring( "cmp eax, 0" ); putnl( );
+	putstring( "jnz itoa_loop" ); putnl( );
 	putstring( "mov eax, 4" ); putnl( );
 	putstring( "mov ebx, 1" ); putnl( );
 	/* TODO: itoa in assembly (yuck!) and print resulting string */
-	putstring( "mov ecx, putint_string" ); putnl( );
+	putstring( "mov ecx, putint_string_fmt" ); putnl( );
 	/* TODO: compute length with a assemble time function sizeof or so.. */
-	putstring( "mov edx, 13" ); putnl( );
+	putstring( "mov edx, 11" ); putnl( );
 	putstring( "int 0x80" ); putnl( );
-	putstring( "ret 4" ); putnl( );
+	putstring( "ret" ); putnl( );
 	putstring( "_start:" ); putnl( );
-	
+
 /*
-		__asm__ volatile( "\
-		push %%ebx\n\
-		push %%ecx\n\
-		push %%edx\n\
-		mov %1, %%eax\n\
-		mov %2, %%ebx\n\
-		mov %3, %%ecx\n\
-		mov %4, %%edx\n\
-		int $0x80\n\
-		mov %%eax, %0\n\
-		pop %%edx\n\
-		pop %%ecx\n\
-		pop %%ebx\n" : "=m"( retval ) : "m"( id ), "m"( arg0 ), "m"( arg1 ), "m"( arg2 )
-		: "eax", "ebx", "ecx", "edx" );		
-		*/
+
+fmt: .string "%s\n"
+
+.lcomm converted, 10
+
+
+	.section .text
+
+.global _start
+
+_start:
+
+	xorl %ecx, %ecx
+	xorl %edi, %edi
+	movl $NUMBER, %eax
+
+itoa_loop:
+	# Limpa para divisão
+	xorl %edx, %edx
+	
+	movl $10, %esi
+	
+	# Agora nós temos o quociente em %eax
+	# e o resto da divisão em %edx
+	idiv %esi
+		
+	# Convertendo para a representação em ASCII
+	addl $48, %edx
+	
+	pushl %edx
+	incl %ecx
+	
+	xorl $0, %eax
+	jnz itoa_loop
+
+rev_loop:
+	popl %eax
+	movl %eax, converted(, %edi, 1)
+	incl %edi
+	decl %ecx
+
+	cmpl $0, %ecx	
+	jnz rev_loop
+	
+	pusha	
+	pushl $converted
+	pushl $fmt
+	call printf
+	addl $8, %esp	
+	popa
+
+	# Exiting
+	movl $1, %eax
+	int $0x80
+ */
 }
 
 void genEpilogue( struct Compiler *compiler )
@@ -836,8 +892,8 @@ void genEpilogue( struct Compiler *compiler )
 		genAddGlob( compiler->generator, sym->name );
 		sym = sym->next;
 	}
-	putstring( "putint_string:" ); putnl( );
-	putstring( "db \"putint test \", 10, 0" ); putnl( );
+	putstring( "putint_string_fmt:" ); putnl( );
+	putstring( "db \"          \", 10, 0" ); putnl( );
 }
 
 /* parser */
@@ -1049,7 +1105,6 @@ void parsePutint( struct Compiler *compiler )
 	node = parseExpression( parser, 0 );
 	parserExpect( parser, S_SEMICOLON, ";" );
 	generateFromAST( compiler->generator, node, NOREG );
-	putstring( "push eax" ); putnl( );
 	putstring( "call putint" ); putnl( );
 	genFreeAllRegs( compiler->generator );
 	freeASTnode( node );
diff --git a/miniany/test1.c b/miniany/test1.c
index d7015e2..707ff16 100644
--- a/miniany/test1.c
+++ b/miniany/test1.c
@@ -4,5 +4,6 @@ int i;
 int j;
 
 i = 12+25/5-2*3; // 25/5 -> 5, 12+5 -> 17, 2*3 -> 6, 17-6 -> 11
-j = i/3+3*4; // 11 / 3 -> 3, 3*4 -> 12, 3+12 -> 15 
 putint i;
+j = i/3+3*4; // 11 / 3 -> 3, 3*4 -> 12, 3+12 -> 15 
+putint j;
-- 
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