diff --git a/programs/develop/ktcc/trunk/libc/math/fmod.c b/programs/develop/ktcc/trunk/libc/math/fmod.c
new file mode 100644
index 0000000000..4e68f19bc2
--- /dev/null
+++ b/programs/develop/ktcc/trunk/libc/math/fmod.c
@@ -0,0 +1,86 @@
+#include <math.h>
+
+double remainder(double numer, double denom)
+{
+	double res;
+	asm("fldl %2;"
+		"fldl %1;"
+		"fprem1;"
+		"fstpl %0;"
+		"fstp %%st;"
+	: "=m"(res)
+	: "m"(numer), "m"(denom)
+	);
+	return res;
+}
+//remainder of 5.3 / 2 is -0.700000
+//remainder of 18.5 / 4.2 is 1.700000
+
+
+
+double fmod(double numer, double denom)
+{
+	double res;
+	asm("fldl %2;"
+		"fldl %1;"
+		"fprem;"
+		"fstpl %0;"
+		"fstp %%st;"
+	: "=m"(res)
+	: "m"(numer), "m"(denom)
+	);
+	return res;
+}
+// fmod of 5.3 / 2 is 1.300000
+// fmod of 18.5 / 4.2 is 1.700000
+
+
+double modf(double x, double *intpart)
+{
+	double res, intp;
+	asm("fldl %2;"
+		"fldl %2;"
+		"frndint;"
+		"fstl %1;"
+		"fxch;"
+		"fsubp %%st, %%st(1);"
+		"fstpl %0"
+	: "=m"(res), "=m"(intp)
+	: "m"(x) 
+	);
+	*intpart = intp;
+	return res;
+}
+
+double ldexp (double x, int expon)
+// = x * 2^expot
+{
+	double res;
+	asm("fildl %2;"
+		"fldl %1;"
+		"fscale;"
+		"fstpl %0;"
+		"fstp %%st;"
+	: "=m"(res)
+	: "m"(x), "m"(expon)
+	);
+
+	return res;
+}
+
+double frexp (double x, int* expon)
+{
+	double res;
+	asm("fldl %2;"
+		"fxtract;"
+		"fstpl %0;"
+		"fistpl %1;"
+		"fstp %%st;"
+	: "=m"(res), "=m"(*expon)
+	: "m"(x)
+	);
+
+//	*expon = (int)ex;
+	return res;
+}
+// 8.000000 = 0.500000 * 2^ 4
diff --git a/programs/develop/ktcc/trunk/samples/asm_ex.c b/programs/develop/ktcc/trunk/samples/asm_ex.c
new file mode 100644
index 0000000000..2a0bc40313
--- /dev/null
+++ b/programs/develop/ktcc/trunk/samples/asm_ex.c
@@ -0,0 +1,68 @@
+/* examples for interoperability with assembler
+
+1. Calling assembler code from .c : see in libc\math any .asm file
+2. Using inline assembler: see \include\kos32sys1.h and libc\math\fmod.c
+- https://gcc.gnu.org/onlinedocs/gcc-4.8.5/gcc/Extended-Asm.html
+- not all constraints from gcc are supported, no "f" or "t" for example
+- not supported clobberring st registers, must manual add "fstp %%st" at end or similar
+- need full suffixes for opcodes, fstpl but not fstp
+
+3. Calling c functions from .asm: see \libc\start\start.asm:99
+Remember: 
+- small ints always passed as int32, floating point params as 64-bit
+- returned structs passed on stack with additional hidden 1st param
+- c functions can use EAX, ECX, EDX without warnings
+- .c default is cdecl calling convention https://en.wikipedia.org/wiki/X86_calling_conventions 
+- dont use fastcall calling convention, tinycc realized it non-conformant way
+- tinycc supports only ELF object files
+
+tcc can be used as a linker
+*/
+
+
+
+
+#include <stdio.h>
+#include <math.h>
+
+
+main()
+{	
+	int i;
+	for (i = 0; i < 20; i++)
+	{
+	printf("------------------------------------------------------\n");
+	printf ( "remainder of 5.3 / 2 is %f\n", remainder (5.3,2) );
+  	printf ( "remainder of 18.5 / 4.2 is %f\n", remainder (18.5,4.2) );
+//remainder of 5.3 / 2 is -0.700000
+//remainder of 18.5 / 4.2 is 1.700000
+
+	printf ( "fmod of 5.3 / 2 is %f\n", fmod (5.3,2) );
+	printf ( "fmod of 18.5 / 4.2 is %f\n", fmod (18.5,4.2) );
+// fmod of 5.3 / 2 is 1.300000
+// fmod of 18.5 / 4.2 is 1.700000
+
+	double param, fractpart, intpart, result;
+	int n;
+
+  	param = 3.14159265;
+  	fractpart = modf (param , &intpart);
+  	printf ("%f = %f + %f \n", param, intpart, fractpart);
+//3.141593 = 3.000000 + 0.141593
+
+ 	param = 0.95;
+	n = 4;
+	result = ldexp (param , n);
+	printf ("%f * 2^%d = %f\n", param, n, result);
+//0.950000 * 2^4 = 15.200000
+
+	param = 8.0;
+	result = frexp (param , &n);
+	printf ("%f = %f * 2^%d\n", param, result, n);
+//8.000000 = 0.500000 * 2^4
+	param = 50;
+	result = frexp (param , &n);
+	printf ("%f = %f * 2^%d\n", param, result, n);
+
+	}    
+}
\ No newline at end of file
diff --git a/programs/develop/ktcc/trunk/source/config.h b/programs/develop/ktcc/trunk/source/config.h
index 85a371d323..6750a92f5d 100644
--- a/programs/develop/ktcc/trunk/source/config.h
+++ b/programs/develop/ktcc/trunk/source/config.h
@@ -4,5 +4,7 @@
 #define TCC_TARGET_I386
 #define ONE_SOURCE
 
+//#define TCC_TARGET_COFF
+
 //#define COMMIT_4ad186c5ef61_IS_FIXED
 //#define CONFIG_TCC_BCHECK
diff --git a/programs/develop/ktcc/trunk/source/libtcc.c b/programs/develop/ktcc/trunk/source/libtcc.c
index ecd90a467e..aaddd9dbc1 100644
--- a/programs/develop/ktcc/trunk/source/libtcc.c
+++ b/programs/develop/ktcc/trunk/source/libtcc.c
@@ -2126,6 +2126,12 @@ ST_FUNC int tcc_parse_args1(TCCState *s, int argc, char **argv)
     int optind = 0;
     ParseArgsState *pas = s->parse_args_state;
 
+/*
+#ifdef TCC_TARGET_MEOS
+// siemargl testing
+	s->output_format = TCC_OUTPUT_FORMAT_COFF;
+#endif
+*/
     while (optind < argc) {
 
         r = argv[optind++];
diff --git a/programs/develop/ktcc/trunk/source/readme_kos32.txt b/programs/develop/ktcc/trunk/source/readme_kos32.txt
index 11831ab263..ccbb37bc8d 100644
--- a/programs/develop/ktcc/trunk/source/readme_kos32.txt
+++ b/programs/develop/ktcc/trunk/source/readme_kos32.txt
@@ -61,7 +61,7 @@ errno.h  - in stdio
 limits.h
 locale.h
 setjmp.h
-signall.h
+signal.h
 time.h  - can use get_tick_count()/100 from kos32sys1.h
 wchar.h
 wctype.h
@@ -70,14 +70,6 @@ wctype.h
 
 functions absent list:
 
-math.h
-frexp
-ldexp
-modf
-fmod
-
-HUGE_VAL
-
 stdio.h:
 remove
 rename
diff --git a/programs/develop/ktcc/trunk/source/tcc.h b/programs/develop/ktcc/trunk/source/tcc.h
index 73f1c1c1a6..99dc3bf310 100644
--- a/programs/develop/ktcc/trunk/source/tcc.h
+++ b/programs/develop/ktcc/trunk/source/tcc.h
@@ -348,6 +348,11 @@ static inline void write64le(unsigned char *p, uint64_t x)
 /* -------------------------------------------- */
 /* include the target specific definitions */
 
+#ifdef TCC_TARGET_COFF
+# include "coff.h"
+#endif
+
+
 #define TARGET_DEFS_ONLY
 #ifdef TCC_TARGET_I386
 # include "i386-gen.c"
@@ -362,7 +367,6 @@ static inline void write64le(unsigned char *p, uint64_t x)
 # include "arm64-gen.c"
 #endif
 #ifdef TCC_TARGET_C67
-# include "coff.h"
 # include "c67-gen.c"
 #endif
 #undef TARGET_DEFS_ONLY
diff --git a/programs/develop/ktcc/trunk/source/tcccoff.c b/programs/develop/ktcc/trunk/source/tcccoff.c
index 1421ca2651..1289690678 100644
--- a/programs/develop/ktcc/trunk/source/tcccoff.c
+++ b/programs/develop/ktcc/trunk/source/tcccoff.c
@@ -876,35 +876,35 @@ ST_FUNC int tcc_load_coff(TCCState * s1, int fd)
     }
 
     if (fread(&file_hdr, FILHSZ, 1, f) != 1)
-	tcc_error("error reading .out file for input");
+	tcc_error("error 1 reading .out file for input");
 
     if (fread(&o_filehdr, sizeof(o_filehdr), 1, f) != 1)
-	tcc_error("error reading .out file for input");
+	tcc_error("error 2 reading .out file for input");
 
     // first read the string table
 
     if (fseek(f, file_hdr.f_symptr + file_hdr.f_nsyms * SYMESZ, SEEK_SET))
-	tcc_error("error reading .out file for input");
+	tcc_error("error 3 reading .out file for input");
 
     if (fread(&str_size, sizeof(int), 1, f) != 1)
-	tcc_error("error reading .out file for input");
+	tcc_error("error 4 reading .out file for input");
 
 
     Coff_str_table = (char *) tcc_malloc(str_size);
 
     if (fread(Coff_str_table, str_size - 4, 1, f) != 1)
-	tcc_error("error reading .out file for input");
+	tcc_error("error 5 reading .out file for input");
 
     // read/process all the symbols
 
     // seek back to symbols
 
     if (fseek(f, file_hdr.f_symptr, SEEK_SET))
-	tcc_error("error reading .out file for input");
+	tcc_error("error 6 reading .out file for input");
 
     for (i = 0; i < file_hdr.f_nsyms; i++) {
 	if (fread(&csym, SYMESZ, 1, f) != 1)
-	    tcc_error("error reading .out file for input");
+	    tcc_error("error 7 reading .out file for input");
 
 	if (csym._n._n_n._n_zeroes == 0) {
 	    name = Coff_str_table + csym._n._n_n._n_offset - 4;