ao-bringup-avr: cleaner stack switching code
[fw/altos] / ao-bringup-avr / ao-switch.c
index 2e3f5a7389d3c910ae80e8e79dfdca7745c3dad3..3ededd95185a9ee7b6079f93940c08e1665b28bb 100644 (file)
  * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
  */
 
-#include <avr/io.h>
-#include <avr/interrupt.h>
-#define TEENSY 0
-#if TEENSY
-#define F_CPU 16000000UL       // 16 MHz
-#else
-#define F_CPU  8000000UL       // 8 MHz
-#endif
-#include <util/delay.h>
-
-#define LEDOUT         PORTB7
-#define LEDPORT                PORTB
-#define LEDDDR         DDRB
-#define LEDDDRPIN      DD7
-
-static void
-adc_start(void);
-
-ISR(TIMER1_COMPA_vect)
-{
-       adc_start();
-}
-
-static void
-timer1_init(void)
-{
-       TCCR1A = ((0 << WGM11) |        /* CTC mode, OCR1A */
-                 (0 << WGM10));        /* CTC mode, OCR1A */
-       TCCR1B = ((0 << ICNC1) |        /* no input capture noise canceler */
-                 (0 << ICES1) |        /* input capture on falling edge (don't care) */
-                 (0 << WGM13) |        /* CTC mode, OCR1A */
-                 (1 << WGM12) |        /* CTC mode, OCR1A */
-                 (3 << CS10));         /* clk/64 from prescaler */
-
-#if TEENSY
-       OCR1A = 2500;                   /* 16MHz clock */
-#else
-       OCR1A = 1250;                   /* 8MHz clock */
-#endif
-
-       TIMSK1 = (1 << OCIE1A);         /* Interrupt on compare match */
-}
-
-static void
-clock_init(void)
-{
-       /* disable RC clock */
-       CLKSEL0 &= ~(1 << RCE);
-
-       /* Disable PLL */
-       PLLCSR &= ~(1 << PLLE);
-
-       /* Enable external clock */
-       CLKSEL0 |= (1 << EXTE);
-
-       /* wait for external clock to be ready */
-       while ((CLKSTA & (1 << EXTON)) == 0)
-               ;
-
-       /* select external clock */
-       CLKSEL0 |= (1 << CLKS);
-
-       /* Disable the clock prescaler */
-       cli();
-       CLKPR = (1 << CLKPCE);
-       CLKPR = 0;
-       sei();
-
-       /* Set up the PLL to use the crystal */
-
-       /* Use primary system clock as PLL source */
-       PLLFRQ = ((0 << PINMUX) |       /* Use primary clock */
-                 (0 << PLLUSB) |       /* No divide by 2 for USB */
-                 (0 << PLLTM0) |       /* Disable high speed timer */
-                 (0x4 << PDIV0));      /* 48MHz PLL clock */
-
-       /* Set the frequency of the crystal */
-#if TEENSY
-       PLLCSR |= (1 << PINDIV);        /* For 16MHz crystal on Teensy board */
-#else
-       PLLCSR &= ~(1 << PINDIV);       /* For 8MHz crystal on TeleScience board */
-#endif
-
-       /* Enable the PLL */
-       PLLCSR |= (1 << PLLE);
-       while (!(PLLCSR & (1 << PLOCK)))
-               ;
-}
-
-static void
-timer0_init(void)
-{
-       TCCR0A = ((1 << COM0A1) |
-                 (0 << COM0A0) |
-                 (1 << WGM01) |
-                 (1 << WGM00));
-
-       OCR0A = 0x10;
-       OCR0B = 0;
-       TIMSK0 = 0;
-
-       TCCR0B = ((0 << WGM02) |
-                 (5 << CS00));
-}
-
-ISR(ADC_vect)
-{
-       OCR0A = ADCH;
-}
-
-#define ADC_CHANNEL    0x25            /* Channel ADC13 */
-#define ADC_CHANNEL_LOW(c)     (((c) & 0x1f) << MUX0)
-#define ADC_CHANNEL_HIGH(c)    ((((c) & 0x20) >> 5) << MUX5)
-
-#define ADCSRA_INIT    ((1 << ADEN) |          /* Enable ADC */                \
-                        (0 << ADATE) |         /* No auto ADC trigger */       \
-                        (1 << ADIE) |          /* Enable interrupt */  \
-                        (6 << ADPS0))          /* Prescale clock by 64 */
-
-#define ADCSRB_INIT    ((0 << ADHSM) |         /* No high-speed mode */ \
-                        (0 << ACME) |          /* Some comparitor thing */ \
-                        (0 << ADTS0))          /* Free running mode (don't care) */
-
-static void
-adc_start(void)
-{
-       ADMUX = ((0 << REFS1) |                         /* AVcc reference */
-                (1 << REFS0) |                         /* AVcc reference */
-                (1 << ADLAR) |                         /* Left-shift results */
-                (ADC_CHANNEL_LOW(ADC_CHANNEL)));       /* Select channel */
-
-       ADCSRB = ADCSRB_INIT | ADC_CHANNEL_HIGH(ADC_CHANNEL);
-
-       ADCSRA = ADCSRA_INIT | (1 << ADSC);             /* Start conversion */
-}
-
-static void
-adc_init(void)
-{
-       ADCSRA = ADCSRA_INIT;
-       ADCSRB = ADCSRB_INIT;
-       DIDR0 |= (1 << 0);
-}
+#include "ao-bringup.h"
 
 #define AO_STACK_SIZE  128
 
-uint8_t        new_stack[512];
-int    stack_count;
-
-#define PUSH8(stack, val)      (*--(stack) = (val))
-
-#define PUSH16(stack, val)     PUSH8(stack, ((uint16_t) (val))); PUSH8(stack, ((uint16_t) (val)) >> 8)
-
-void
-count(int count)
-{
-
-}
+#define PUSH8(stack, val)      (*((stack)--) = (val))
 
 void
 blink(void)
@@ -183,100 +30,89 @@ blink(void)
        }
 }
 
-void
-function(void)
-{
-       return;
-}
 
-void
-init_stack(void (*f) (void))
+uint8_t *
+init_stack(uint8_t *stack_base, int size, void (*f) (void))
 {
-       uint8_t         *stack = new_stack + AO_STACK_SIZE;
-       uint8_t         i;
+       uint8_t         *stack = stack_base + size - 1;
+       uint16_t        a;
+       uint8_t         h, l;
 
        /* Return address */
-       PUSH16(stack, f);
+       a = (uint16_t) f;
+       l = a;
+       h = a >> 8;
+       PUSH8(stack, l);
+       PUSH8(stack, h);
 
-#if 0
        /* Clear register values */
-       i = 32;
-       while (i--)
+       l = 32;
+       while (l--)
                PUSH8(stack, 0);
 
        /* SREG with interrupts enabled */
        PUSH8(stack, 0x80);
-#endif
-       stack_count = stack - new_stack;
+       return stack;
 }
 
 void
-switch_stack(void) __attribute__((naked));
+switch_stack(uint8_t *sp) __attribute__((naked));
 
 void
-switch_stack(void)
+switch_stack(uint8_t *sp)
 {
-#if 0
-       uint16_t        a;
-       uint8_t         l, h;
-
-       a = (uint16_t) function;
-       l = a;
-       h = a >> 8;
-       asm("push %0" : : "r" (l));
-       asm("push %0" : : "r" (h));
-       asm("ret");
-#endif
-#if 0
-       asm("push r31; push r30");
-       asm("push r29; push r28; push r27; push r26; push r25");
-       asm("push r24; push r23; push r22; push r21; push r20");
-       asm("push r19; push r18; push r17; push r16; push r15");
-       asm("push r14; push r13; push r12; push r11; push r10");
-       asm("push r9; push r8; push r7; push r6; push r5");
-       asm("push r4; push r3; push r2; push r1; push r0");
-       asm("in r0, __SREG__" "\n\t"
-           "push r0");
-#endif
-       uint8_t *sp = (new_stack + stack_count);
        uint8_t sp_l, sp_h;
 
        sp_l = (uint16_t) sp;
        sp_h = ((uint16_t) sp) >> 8;
-       asm("out __SP_H__,%0" : : "r" (sp_h) );
-       asm("out __SP_L__,%0" : : "r" (sp_l) );
-       blink();
-#if 0
-       asm("pop r0"    "\n\t"
-           "out __SREG__, r0");
-       asm("pop r0; pop r1; pop r2; pop r3; pop r4");
-       asm("pop r5; pop r6; pop r7; pop r8; pop r9");
-       asm("pop r10; pop r11; pop r12; pop r13; pop r14");
-       asm("pop r15; pop r16; pop r17; pop r18; pop r19");
-       asm("pop r20; pop r21; pop r22; pop r23; pop r24");
-       asm("pop r25; pop r26; pop r27; pop r28; pop r29");
-       asm("pop r30; pop r31");
-#endif
-       asm("ret");
+       asm volatile ("out __SP_H__,%0" : : "r" (sp_h) );
+       asm volatile ("out __SP_L__,%0" : : "r" (sp_l) );
+       asm volatile("pop r0"   "\n\t"
+                    "out __SREG__, r0");
+       asm volatile("pop r0" "\n\t"
+                    "pop r1" "\n\t"
+                    "pop r2" "\n\t"
+                    "pop r3" "\n\t"
+                    "pop r4");
+       asm volatile("pop r5" "\n\t"
+                    "pop r6" "\n\t"
+                    "pop r7" "\n\t"
+                    "pop r8" "\n\t"
+                    "pop r9");
+       asm volatile("pop r10" "\n\t"
+                    "pop r11" "\n\t"
+                    "pop r12" "\n\t"
+                    "pop r13" "\n\t"
+                    "pop r14");
+       asm volatile("pop r15" "\n\t"
+                    "pop r16" "\n\t"
+                    "pop r17" "\n\t"
+                    "pop r18" "\n\t"
+                    "pop r19");
+       asm volatile("pop r20" "\n\t"
+                    "pop r21" "\n\t"
+                    "pop r22" "\n\t"
+                    "pop r23" "\n\t"
+                    "pop r24");
+       asm volatile("pop r25" "\n\t"
+                    "pop r26" "\n\t"
+                    "pop r27" "\n\t"
+                    "pop r28" "\n\t"
+                    "pop r29");
+       asm volatile("pop r30" "\n\t"
+                    "pop r31");
+       asm volatile("ret");
 }
 
-void back(void)
-{
-       switch_stack();
-       blink();
-}
+uint8_t        new_stack[512];
 
 void main(void)
 {
-#if 0
-       clock_init();
-       adc_init();
-       timer1_init();
-       timer0_init();
-#endif
+       uint8_t *stack;
+       ao_bringup_init();
 
-       LEDDDR |= (1 << LEDDDRPIN);
+       printf("starting\n");
 
-       init_stack(blink);
-       switch_stack();
+       stack = init_stack(new_stack, sizeof (new_stack), blink);
+       switch_stack(stack);
 }