Clock out SPI data according to SPCR/SPSR

diff --git a/simavr/sim/avr_spi.c b/simavr/sim/avr_spi.c
index e97d824..da96f29 100644 (file)
--- a/simavr/sim/avr_spi.c
+++ b/simavr/sim/avr_spi.c
@@ -2,6 +2,7 @@
        avr_spi.c
 
        Copyright 2008, 2009 Michel Pollet <buserror@gmail.com>
+       Modified 2020 by VintagePC <https://github.com/vintagepc> to support clock divisors
 
        This file is part of simavr.
 
@@ -25,7 +26,7 @@
 static avr_cycle_count_t avr_spi_raise(struct avr_t * avr, avr_cycle_count_t when, void * param)
 {
        avr_spi_t * p = (avr_spi_t *)param;
-       
+
        if (avr_regbit_get(avr, p->spe)) {
                // in master mode, any byte is sent as it comes..
                if (avr_regbit_get(avr, p->mstr)) {
@@ -55,7 +56,13 @@ static void avr_spi_write(struct avr_t * avr, avr_io_addr_t addr, uint8_t v, voi
                avr_regbit_clear(avr, p->spi.raised);
 
                avr_core_watch_write(avr, addr, v);
-               avr_cycle_timer_register_usec(avr, 100, avr_spi_raise, p); // should be speed dependent
+               uint16_t uiClkShift = _avr_spi_clkdiv[avr->data[p->r_spcr]&0b11];
+               // If master && 2X, double rate (half divisor)
+               if (avr_regbit_get(avr, p->mstr) && avr_regbit_get(avr, p->spr[2]))
+                       uiClkShift>>=1;
+
+               // We can wait directly in clockshifts, it is a divisor, so /4 means 4 avr cycles to clock out one bit.
+               avr_cycle_timer_register(avr, uiClkShift<<3, avr_spi_raise, p); // *8 since 8 clocks to a byte.
        }
 }
 
@@ -72,7 +79,7 @@ static void avr_spi_irq_input(struct avr_irq_t * irq, uint32_t value, void * par
        p->input_data_register = value;
        avr_raise_interrupt(avr, &p->spi);
 
-       // if in slave mode, 
+       // if in slave mode,
        // 'output' the byte only when we received one...
        if (!avr_regbit_get(avr, p->mstr)) {
                avr_raise_irq(p->io.irq + SPI_IRQ_OUTPUT, avr->data[p->r_spdr]);
@@ -108,4 +115,3 @@ void avr_spi_init(avr_t * avr, avr_spi_t * p)
        avr_register_io_write(avr, p->r_spdr, avr_spi_write, p);
        avr_register_io_read(avr, p->r_spdr, avr_spi_read, p);
 }
-

diff --git a/simavr/sim/avr_spi.h b/simavr/sim/avr_spi.h
index 23ff78f..933d405 100644 (file)
--- a/simavr/sim/avr_spi.h
+++ b/simavr/sim/avr_spi.h
@@ -2,6 +2,7 @@
        avr_spi.h
 
        Copyright 2008, 2009 Michel Pollet <buserror@gmail.com>
+       Modified 2020 by VintagePC <https://github.com/vintagepc> to support clock divisors
 
        This file is part of simavr.
 
@@ -45,11 +46,11 @@ typedef struct avr_spi_t {
        avr_io_addr_t   r_spdr;                 // data register
        avr_io_addr_t   r_spcr;                 // control register
        avr_io_addr_t   r_spsr;                 // status register
-       
+
        avr_regbit_t spe;               // spi enable
        avr_regbit_t mstr;              // master/slave
        avr_regbit_t spr[4];    // clock divider
-       
+
        avr_int_vector_t spi;   // spi interrupt
 
        uint8_t         input_data_register;
@@ -103,4 +104,6 @@ void avr_spi_init(avr_t * avr, avr_spi_t * port);
 };
 #endif
 
+static const uint8_t _avr_spi_clkdiv[4] = {4,16,64,128};
+
 #endif /*__AVR_SPI_H__*/