add timer example

timer/Makefile

@@ -0,0 +1,34 @@
+AS		= $(VASM)
+CC		= $(VC)
+LD		= $(VLINK)
+
+ASFLAGS		:= -quiet -Fhunk -kick1hunks -nosym -m68000 -no-opt
+CFLAGS		:= -v -O2 -size -cpu=68060 -c99 -k -sc -DDEBUG
+LDFLAGS		:= -sc -Bstatic -Cvbcc -nostdlib -Rshort -b amigahunk -s
+
+TARGET		:= timer
+OBJECTS		:= main.o timer.o
+INCLUDE 	:= $(wildcard *.h) $(wildcard *.s)
+
+CRT0		=  $(VBCC)/targets/m68k-amigaos/lib/startup.o  
+LDLIBS		= -L$(VBCC)/targets/m68k-amigaos/lib -lvc
+
+.EXPORT_ALL_VARIABLES:
+
+.PHONY: clean
+
+all: $(TARGET)
+
+clean:
+	rm -f $(TARGET) $(OBJECTS) $(OBJECTS:.o=.asm) *.txt
+
+$(TARGET) : $(OBJECTS) Makefile | buildenv
+	$(LD) $(LDFLAGS) $(CRT0) $(OBJECTS) $(LDLIBS) -o $@ -M$@.txt 
+
+%.o: %.c $(INCLUDE) Makefile | buildenv
+	$(CC) $(CFLAGS) -c $< -o $@
+
+%.o: %.s Makefile | buildenv
+	$(AS) $< -o $@ -L $<.txt $(ASFLAGS) -I $(INC_ASM)
+
+include ../Makefile.build

timer/main.c

@@ -0,0 +1,43 @@
+#include <stdio.h>
+#include <stdint.h>
+
+#include <proto/exec.h>
+
+#define NUMRUNS (10)
+#define NUMITERATIONS (10000)
+
+uint32_t runAsmCode(__reg("d0") uint32_t iterations);
+uint32_t getCpuCycle() = 
+	"\tmoveq.l\t#0,d0\n"
+	"\trept 100\n"
+	"\tsub.l\t$40400000,d0\t;read CPU clock\n"
+	"\tadd.l\t$40400000,d0\n"
+	"\tendr\n";
+
+static uint32_t sample()
+{
+	return getCpuCycle();
+}
+
+int main()
+{
+	uint32_t result[NUMRUNS];
+
+	// Calibrate the cost of reading the cycle counter
+	Disable();
+	for (int i = 0; i < NUMRUNS; ++i)
+		result[i] = sample();
+	Enable();
+	for (int i = 0; i < NUMRUNS; ++i)
+		printf("REPT 100 took %d cycles\n", (int)result[i]);
+
+	// Measure the 5c/7instr loop
+	Disable();
+	for (int i = 0; i < NUMRUNS; ++i)
+		result[i] = runAsmCode(NUMITERATIONS);
+	Enable();
+	for (int i = 0; i < NUMRUNS; ++i)
+		printf("%d iterations took %d cycles\n", NUMITERATIONS, (int)result[i]);
+
+	return 0;
+}

timer/timer.s

@@ -0,0 +1,31 @@
+
+; Example program
+; This runs a 5-cycle code loop for N iterations (provided in D0),
+; and then returns (in D0) the number of CPU cycles used.
+
+	PUBLIC	_runAsmCode
+
+_runAsmCode:
+
+	bset.b	#1,$bfe001		; trigger logic analyzer
+	tst.b	$bfe001			; delay due to SIO on the 060db
+	move.l	$40400000,a0		; sample cpu clock counter
+
+.iter:
+	addx.l	d1,d1			; pOEP-only
+	addx.l	d1,d1			; pOEP-only
+	addx.l	d1,d1			; pOEP-only
+	addx.l	d1,d1			; pOEP-only
+
+	add.l	d1,d1			; pOEP|sOEP
+	subq.l	#1,d0			; pOEP|sOEP
+	bne.s	.iter			; is predicted and folded, takes 0 cycles
+
+	sub.l	$40400000,a0		; sample cpu clock counter
+	bclr.b	#1,$bfe001		; reset logic analyzer
+
+	moveq.l	#0,d0
+	sub.l	a0,d0
+
+	rts
+