Add shared emulator services, waveform generation and STM32 USB boot ports

c/set-protocol/ports/stm32f407-wavegen/set_wave_f407.h

@@ -0,0 +1,12 @@
+#ifndef SET_WAVE_F407_H
+#define SET_WAVE_F407_H
+#include "../../include/set_wavegen.h"
+/* Owns PA4, DAC channel 1, TIM6 and DMA1 stream 5/channel 7.
+ * timer_hz is TIM6 input clock (twice APB1 when APB1 prescaler !=1).
+ * Rate: 1..SET_WAVE_MAX_RATE (1 MS/s), exact divisors of timer_hz only.
+ * Context and sample buffer must outlive playback; buffer must be in SRAM. */
+typedef struct { uint32_t timer_hz; } set_wave_f407;
+set_wave_port set_wave_f407_port(set_wave_f407 *context);
+/* Nonzero on DMA error or DAC underrun; caller stops state on failure. */
+int set_wave_f407_fault(void);
+#endif