feat(pps): add adaptive disciplined timing loop

soc/software/gps_system/Makefile

@@ -5,7 +5,7 @@ TARGET := gps_system
 # directory previously compiled every GPS_LOG call out and produced a silent
 # UART image.
 GPS_DEBUG ?= 1
-GPS_DEBUG_LEVEL ?= 4
+GPS_DEBUG_LEVEL ?= 1
 GPS_BUILD_ID ?= $(shell git describe --always --dirty --abbrev=12 2>/dev/null || printf unknown)
 
 # The current Genesys2 Rocket/fabric domain that clocks the UART is 50 MHz.
@@ -71,6 +71,8 @@ APP_SRCS := \
 	src/gps/gps_time_anchor.c \
 	src/gps/gps_nav_epoch.c \
 	src/gps/gps_pps.c \
+	src/gps/gps_pps_quality.c \
+	src/gps/gps_pps_time_filter.c \
 	src/gps/gps_tracking_measurement.c \
 	src/gps/linked_list.c \
 	src/gps/NavEquations.c \
@@ -79,6 +81,7 @@ APP_SRCS := \
 BSP_SRCS := init.c uart.c plic.c irq.c spi_flash.c pmod_spi.c
 
 GPS_NAV_SOLVE_TIMER_TICKS ?= 10
+GPS_PPS_STATUS_LOG_INTERVAL ?= 10
 
 include ../common/app.mk
 
@@ -90,7 +93,8 @@ CFLAGS += $(IMU_BACKEND_CFLAG) \
 	-DIMU_GYRO_FS_DPS=$(IMU_GYRO_FS_DPS) \
 	-DGPS_ESKF_ENABLE=$(GPS_ESKF_ENABLE) \
 	-DIMU_CORRECTED_PUBLISH_EVERY_N_SAMPLES=$(IMU_CORRECTED_PUBLISH_EVERY_N_SAMPLES) \
-	-DGPS_NAV_SOLVE_TIMER_TICKS=$(GPS_NAV_SOLVE_TIMER_TICKS)
+	-DGPS_NAV_SOLVE_TIMER_TICKS=$(GPS_NAV_SOLVE_TIMER_TICKS) \
+	-DGPS_PPS_STATUS_LOG_INTERVAL=$(GPS_PPS_STATUS_LOG_INTERVAL)
 LDLIBS += -lm
 
 ifeq ($(GPS_DEBUG),1)