From 3e4d8f433239c40311037616b1b8833a06651ae0 Mon Sep 17 00:00:00 2001
From: Arne Schwabe <arne@rfc2549.org>
Date: Mon, 16 Apr 2012 19:21:14 +0200
Subject: Initial import

---
 openssl/crypto/perlasm/readme | 124 ++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 124 insertions(+)
 create mode 100644 openssl/crypto/perlasm/readme

(limited to 'openssl/crypto/perlasm/readme')

diff --git a/openssl/crypto/perlasm/readme b/openssl/crypto/perlasm/readme
new file mode 100644
index 00000000..f02bbee7
--- /dev/null
+++ b/openssl/crypto/perlasm/readme
@@ -0,0 +1,124 @@
+The perl scripts in this directory are my 'hack' to generate
+multiple different assembler formats via the one origional script.
+
+The way to use this library is to start with adding the path to this directory
+and then include it.
+
+push(@INC,"perlasm","../../perlasm");
+require "x86asm.pl";
+
+The first thing we do is setup the file and type of assember
+
+&asm_init($ARGV[0],$0);
+
+The first argument is the 'type'.  Currently
+'cpp', 'sol', 'a.out', 'elf' or 'win32'.
+Argument 2 is the file name.
+
+The reciprocal function is
+&asm_finish() which should be called at the end.
+
+There are 2 main 'packages'. x86ms.pl, which is the microsoft assembler,
+and x86unix.pl which is the unix (gas) version.
+
+Functions of interest are:
+&external_label("des_SPtrans");	declare and external variable
+&LB(reg);			Low byte for a register
+&HB(reg);			High byte for a register
+&BP(off,base,index,scale)	Byte pointer addressing
+&DWP(off,base,index,scale)	Word pointer addressing
+&stack_push(num)		Basically a 'sub esp, num*4' with extra
+&stack_pop(num)			inverse of stack_push
+&function_begin(name,extra)	Start a function with pushing of
+				edi, esi, ebx and ebp.  extra is extra win32
+				external info that may be required.
+&function_begin_B(name,extra)	Same as norma function_begin but no pushing.
+&function_end(name)		Call at end of function.
+&function_end_A(name)		Standard pop and ret, for use inside functions
+&function_end_B(name)		Call at end but with poping or 'ret'.
+&swtmp(num)			Address on stack temp word.
+&wparam(num)			Parameter number num, that was push
+				in C convention.  This all works over pushes
+				and pops.
+&comment("hello there")		Put in a comment.
+&label("loop")			Refer to a label, normally a jmp target.
+&set_label("loop")		Set a label at this point.
+&data_word(word)		Put in a word of data.
+
+So how does this all hold together?  Given
+
+int calc(int len, int *data)
+	{
+	int i,j=0;
+
+	for (i=0; i<len; i++)
+		{
+		j+=other(data[i]);
+		}
+	}
+
+So a very simple version of this function could be coded as
+
+	push(@INC,"perlasm","../../perlasm");
+	require "x86asm.pl";
+	
+	&asm_init($ARGV[0],"cacl.pl");
+
+	&external_label("other");
+
+	$tmp1=	"eax";
+	$j=	"edi";
+	$data=	"esi";
+	$i=	"ebp";
+
+	&comment("a simple function");
+	&function_begin("calc");
+	&mov(	$data,		&wparam(1)); # data
+	&xor(	$j,		$j);
+	&xor(	$i,		$i);
+
+	&set_label("loop");
+	&cmp(	$i,		&wparam(0));
+	&jge(	&label("end"));
+
+	&mov(	$tmp1,		&DWP(0,$data,$i,4));
+	&push(	$tmp1);
+	&call(	"other");
+	&add(	$j,		"eax");
+	&pop(	$tmp1);
+	&inc(	$i);
+	&jmp(	&label("loop"));
+
+	&set_label("end");
+	&mov(	"eax",		$j);
+
+	&function_end("calc");
+
+	&asm_finish();
+
+The above example is very very unoptimised but gives an idea of how
+things work.
+
+There is also a cbc mode function generator in cbc.pl
+
+&cbc(	$name,
+	$encrypt_function_name,
+	$decrypt_function_name,
+	$true_if_byte_swap_needed,
+	$parameter_number_for_iv,
+	$parameter_number_for_encrypt_flag,
+	$first_parameter_to_pass,
+	$second_parameter_to_pass,
+	$third_parameter_to_pass);
+
+So for example, given
+void BF_encrypt(BF_LONG *data,BF_KEY *key);
+void BF_decrypt(BF_LONG *data,BF_KEY *key);
+void BF_cbc_encrypt(unsigned char *in, unsigned char *out, long length,
+        BF_KEY *ks, unsigned char *iv, int enc);
+
+&cbc("BF_cbc_encrypt","BF_encrypt","BF_encrypt",1,4,5,3,-1,-1);
+
+&cbc("des_ncbc_encrypt","des_encrypt","des_encrypt",0,4,5,3,5,-1);
+&cbc("des_ede3_cbc_encrypt","des_encrypt3","des_decrypt3",0,6,7,3,4,5);
+
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