From b1b69c8b73cbffb56c688f6a968d144b642cdff2 Mon Sep 17 00:00:00 2001 From: Keith Packard Date: Fri, 20 Mar 2015 15:09:20 -0700 Subject: altos/stmf0: Have fast ADC ring buffer code use wrap-around Instead of requiring that the whole set of returned values fit precisely in the ring, allow for wrap-around so that we can fetch an odd number of ADC values. The previous version required that the fetch amount always be a factor of the ADC buffer size. Signed-off-by: Keith Packard --- src/drivers/ao_trng.c | 11 +++++++---- src/drivers/ao_trng_send.c | 11 +++++++---- 2 files changed, 14 insertions(+), 8 deletions(-) (limited to 'src/drivers') diff --git a/src/drivers/ao_trng.c b/src/drivers/ao_trng.c index db742928..e69cd30b 100644 --- a/src/drivers/ao_trng.c +++ b/src/drivers/ao_trng.c @@ -29,7 +29,8 @@ ao_trng_fetch(void) int usb_buf_id; uint16_t i; uint16_t *buf; - uint32_t *rnd; + uint16_t t; + uint32_t *rnd = (uint32_t *) ao_adc_ring; if (!buffer[0]) { buffer[0] = ao_usb_alloc(); @@ -50,10 +51,12 @@ ao_trng_fetch(void) ao_led_on(AO_LED_TRNG_READ); while (count--) { - rnd = (uint32_t *) ao_adc_get(AO_USB_IN_SIZE); /* one 16-bit value per output byte */ + t = ao_adc_get(AO_USB_IN_SIZE) >> 1; /* one 16-bit value per output byte */ buf = buffer[usb_buf_id]; - for (i = 0; i < AO_USB_IN_SIZE / sizeof (uint16_t); i++) - *buf++ = ao_crc_in_32_out_16(*rnd++); + for (i = 0; i < AO_USB_IN_SIZE / sizeof (uint16_t); i++) { + *buf++ = ao_crc_in_32_out_16(rnd[t]); + t = (t + 1) & ((AO_ADC_RING_SIZE>>1) - 1); + } ao_adc_ack(AO_USB_IN_SIZE); ao_led_toggle(AO_LED_TRNG_READ|AO_LED_TRNG_WRITE); ao_usb_write(buffer[usb_buf_id], AO_USB_IN_SIZE); diff --git a/src/drivers/ao_trng_send.c b/src/drivers/ao_trng_send.c index 34a8a981..bac6035c 100644 --- a/src/drivers/ao_trng_send.c +++ b/src/drivers/ao_trng_send.c @@ -27,7 +27,8 @@ ao_trng_send(void) int usb_buf_id; uint16_t i; uint16_t *buf; - uint32_t *rnd; + uint16_t t; + uint32_t *rnd = (uint32_t *) ao_adc_ring; if (!buffer[0]) { buffer[0] = ao_usb_alloc(); @@ -42,10 +43,12 @@ ao_trng_send(void) for (;;) { ao_led_on(AO_LED_TRNG_ACTIVE); - rnd = (uint32_t *) ao_adc_get(AO_USB_IN_SIZE); /* one 16-bit value per output byte */ + t = ao_adc_get(AO_USB_IN_SIZE) >> 1; /* one 16-bit value per output byte */ buf = buffer[usb_buf_id]; - for (i = 0; i < AO_USB_IN_SIZE / sizeof (uint16_t); i++) - *buf++ = ao_crc_in_32_out_16(*rnd++); + for (i = 0; i < AO_USB_IN_SIZE / sizeof (uint16_t); i++) { + *buf++ = ao_crc_in_32_out_16(rnd[t]); + t = (t + 1) & ((AO_ADC_RING_SIZE>>1) - 1); + } ao_adc_ack(AO_USB_IN_SIZE); ao_led_off(AO_LED_TRNG_ACTIVE); ao_usb_write(buffer[usb_buf_id], AO_USB_IN_SIZE); -- cgit v1.2.3