It seems to me that you are missing the printf_flt. Try adding:
LDFLAGS+=-lm -Wl,-u,vfprintf -lprintf_flt
Since the avr are so tiny on rom and ram the developers made a version
without float support
to reduce resources usage when possible.
Best Marcelo.
2011/1/14 Thomas D. Dean <tomd...@speakeasy.org>
> I am attempting to compare the uM-FPU and avr-libc floating point times.
> I think I am missing something, but, what?
>
> See the code at the bottom.
>
> The code is compiled with:
> avr-gcc -Os -mmcu=atmega128 -c -o main.o main.c
> avr-gcc -Os -mmcu=atmega128 main.o -o main.elf -lc
> avr-objcopy --only-section .text --only-section .data \
> --output-target=ihex main.elf main.hex
>
> The output on the sio is:
>
> AVR Floating Point Tests
> AVR Floating Point Tests
> ssprintf ? 58
> Fporta ? 6
> Fmul ? 18
> Fadd ? 16
> Fdiv ? 0
> Fsin ? 0
> Llint -235875775 0
>
> All the floating point numbers are converted to '?' It appears the
> floating point conversion is not done???
>
> If I link with
> avr-gcc -Os -mmcu=atmega128 main.o -o main.elf \
> -L/usr/lib/avr/lib/avr51 -lc -lm
> I get the same code, looking at the output of avr-objdump. It appears
> that avr-gcc either uses the intrinsic code or always uses libm.a.
> Which?
>
> What am I doing wrong?
>
> tomdean
>
> === Code =============================================================
>
> // main.c - part of atmega float test
> //
> // 20110113 tomdean - initial version
> // This code is GPL
> //
> // $Id$
>
> ////////////////////////////////////////////////////////
> // includes
> #include <avr/io.h> // port definitions
> #include <math.h> // math functions
> #include <string.h> // string functions
> #include <avr/interrupt.h> // interrupt
> #include <stdio.h> // sprintf
> // need two defines before setbaud
> #define F_CPU 16000000L
> #define BAUD 38400
> #include <util/setbaud.h>
>
> ////////////////////////////////////////////////////////
> // defines
> #define TRACE_PORT PORTB
> #define TRACE_DDR DDRB
> #define TRACE_ON(n) TRACE_PORT |= _BV((n))
> #define TRACE_OFF(n) TRACE_PORT &= ~_BV((n))
>
> ////////////////////////////////////////////////////////
> // globals
> uint16_t ovfl;
> uint16_t tcnt;
> uint16_t tmp;
> uint16_t start, delta[10];
> uint8_t sio_buf[64];
>
> ////////////////////////////////////////////////////////
> // serial init
> void serial_init() {
> UBRR0H = UBRRH_VALUE;
> UBRR0L = UBRRL_VALUE;
> UCSR0B = _BV(RXEN0) | _BV(TXEN0);
> // UCSR0C = _BV(USBS) | _BV(UCSZ1) | _BV(UCSZ0);
> return;
> }
>
> ////////////////////////////////////////////////////////
> // counter1 init
> void counter1_init() {
> TCCR1B = _BV(CS11); // clk/8 = 1/2 usec ticks
> TIMSK |= _BV(TOIE1); // counter1 overflow interrupt
> return;
> }
>
>
> ////////////////////////////////////////////////////////
> // counter 1 ISR
> ISR(SIG_OVERFLOW1) {
> ovfl++;
> }
>
> ////////////////////////////////////////////////////////
> // usec - return the number of usec since we started.
> uint32_t usec() {
> tcnt = TCNT1;
> tmp = ovfl;
> return (uint32_t)tcnt + (uint32_t)65536*(uint32_t)tmp;
> }
>
> /////////////////////////////////////////////////////////////
> // serial_recv
> uint8_t serial_recv() {
> while (!(UCSR0A & _BV(RXC0)));
> /* return the char */
> return UDR0;
> }
>
> /////////////////////////////////////////////////////////////
> // serial_send
> void serial_send(uint8_t c) {
> while (!(UCSR0A & _BV(UDRE0)));
> /* send the char */
> UDR0 = c;
> return;
> }
>
> /////////////////////////////////////////////////////////////
> // serial_print
> void serial_print(uint8_t *msg) {
> while (*msg != 0)
> serial_send (*msg++);
> return;
> }
>
> ////////////////////////////////////////////////////////
> // initialize
> void initialize(void) {
> TRACE_DDR = 0xff; // all output
> serial_init();
> counter1_init();
> }
>
> ////////////////////////////////////////////////////////
> // main
> int main() {
> float pi, fmul, fadd, fdiv, fsin;
> float ftcnt1;
> long long ltcnt1, ltcnt2, llint;
> char ch;
>
> initialize();
> ch = serial_recv();
> serial_print("AVR Floating Point Tests\n");
>
> while(1) {
> ch = serial_recv();
> serial_print("AVR Floating Point Tests\n");
> // Start
> TRACE_PORT ^= _BV(0);
> //
> TRACE_ON(1);
> start = usec();
> ftcnt1 = (float)TCNT1; // sort of like a random number
> delta[0] = usec() - start;
> TRACE_OFF(1);
>
> TRACE_ON(2);
> start = usec();
> sprintf(sio_buf,"%f",M_PI);
> delta[1] = usec() - start;
> TRACE_OFF(2);
>
> TRACE_ON(3);
> start = usec();
> fmul = ftcnt1 * M_PI;
> delta[2] = usec() - start;
> TRACE_OFF(3);
>
> TRACE_ON(4);
> start = usec();
> fadd = fmul + ftcnt1;
> delta[3] = usec() - start;
> TRACE_OFF(4);
>
> TRACE_ON(5);
> start = usec();
> fdiv = fmul/fadd;
> delta[4] = usec() - start;
> TRACE_OFF(5);
>
> TRACE_ON(6);
> start = usec();
> fsin = sin(fadd);
> delta[5] = usec() - start;
> TRACE_OFF(6);
>
> ltcnt1 = (long long)TCNT1;
> ltcnt2 = (long long)TCNT1;
> TRACE_OFF(7);
> start = usec();
> llint = ltcnt1 * ltcnt2;
> delta[6] = usec() - start;
> TRACE_OFF(7);
>
> serial_print("sprintf ");
> serial_print(sio_buf);
> sprintf(sio_buf," %d\n",delta[1]);
> serial_print(sio_buf);
>
> sprintf(sio_buf,"Ftcnt1 %f %d\n",ftcnt1, delta[0]);
> serial_print(sio_buf);
>
> sprintf(sio_buf,"Fmul %f %d\n",fmul,delta[2]);
> serial_print(sio_buf);
>
> sprintf(sio_buf,"Fadd %f %d\n",fadd, delta[3]);
> serial_print(sio_buf);
>
> sprintf(sio_buf,"Fdiv %f %d\n",fdiv,delta[4]);
> serial_print(sio_buf);
>
> sprintf(sio_buf,"Fsin %f %d\n",fsin,delta[5]);
> serial_print(sio_buf);
>
> sprintf(sio_buf,"Llint %ld %d\n",llint,delta[6]);
> serial_print(sio_buf);
>
> // reset the clock
> ovfl = 0;
>
> }
> // never get here ...
> return 0;
> }
>
>
>
> _______________________________________________
> AVR-GCC-list mailing list
> AVR-GCC-list@nongnu.org
> http://lists.nongnu.org/mailman/listinfo/avr-gcc-list
>
--
[]s,
Marcelo
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