Merge pull request #1707 from pennae/rp-pio-load

rp: relocate programs implicitly during load

11 files changed, 200 insertions, 71 deletions

diff --git a/cyw43-pio/src/lib.rs b/cyw43-pio/src/lib.rs
index dca30c74d..830a5b44a 100644
--- a/cyw43-pio/src/lib.rs
+++ b/cyw43-pio/src/lib.rs
@@ -8,7 +8,6 @@ use cyw43::SpiBusCyw43;
 use embassy_rp::dma::Channel;
 use embassy_rp::gpio::{Drive, Level, Output, Pin, Pull, SlewRate};
 use embassy_rp::pio::{Common, Config, Direction, Instance, Irq, PioPin, ShiftDirection, StateMachine};
-use embassy_rp::relocate::RelocatedProgram;
 use embassy_rp::{pio_instr_util, Peripheral, PeripheralRef};
 use fixed::FixedU32;
 use pio_proc::pio_asm;
@@ -88,8 +87,6 @@ where
             ".wrap"
         );
 
-        let relocated = RelocatedProgram::new(&program.program);
-
         let mut pin_io: embassy_rp::pio::Pin<PIO> = common.make_pio_pin(dio);
         pin_io.set_pull(Pull::None);
         pin_io.set_schmitt(true);
@@ -102,7 +99,8 @@ where
         pin_clk.set_slew_rate(SlewRate::Fast);
 
         let mut cfg = Config::default();
-        cfg.use_program(&common.load_program(&relocated), &[&pin_clk]);
+        let loaded_program = common.load_program(&program.program);
+        cfg.use_program(&loaded_program, &[&pin_clk]);
         cfg.set_out_pins(&[&pin_io]);
         cfg.set_in_pins(&[&pin_io]);
         cfg.set_set_pins(&[&pin_io]);
@@ -142,7 +140,7 @@ where
             sm,
             irq,
             dma: dma.into_ref(),
-            wrap_target: relocated.wrap().target,
+            wrap_target: loaded_program.wrap.target,
         }
     }
 
diff --git a/embassy-rp/src/lib.rs b/embassy-rp/src/lib.rs
index ebec9fec6..45156458d 100644
--- a/embassy-rp/src/lib.rs
+++ b/embassy-rp/src/lib.rs
@@ -33,7 +33,7 @@ pub mod watchdog;
 // TODO: move `pio_instr_util` and `relocate` to inside `pio`
 pub mod pio;
 pub mod pio_instr_util;
-pub mod relocate;
+pub(crate) mod relocate;
 
 // Reexports
 pub use embassy_hal_internal::{into_ref, Peripheral, PeripheralRef};
diff --git a/embassy-rp/src/pio.rs b/embassy-rp/src/pio.rs
index 464988b27..3de398af7 100644
--- a/embassy-rp/src/pio.rs
+++ b/embassy-rp/src/pio.rs
@@ -11,7 +11,7 @@ use fixed::types::extra::U8;
 use fixed::FixedU32;
 use pac::io::vals::Gpio0ctrlFuncsel;
 use pac::pio::vals::SmExecctrlStatusSel;
-use pio::{SideSet, Wrap};
+use pio::{Program, SideSet, Wrap};
 
 use crate::dma::{Channel, Transfer, Word};
 use crate::gpio::sealed::Pin as SealedPin;
@@ -734,23 +734,67 @@ pub struct InstanceMemory<'d, PIO: Instance> {
 
 pub struct LoadedProgram<'d, PIO: Instance> {
     pub used_memory: InstanceMemory<'d, PIO>,
-    origin: u8,
-    wrap: Wrap,
-    side_set: SideSet,
+    pub origin: u8,
+    pub wrap: Wrap,
+    pub side_set: SideSet,
+}
+
+#[derive(Clone, Copy, PartialEq, Eq, Debug)]
+#[cfg_attr(feature = "defmt", derive(defmt::Format))]
+pub enum LoadError {
+    /// Insufficient consecutive free instruction space to load program.
+    InsufficientSpace,
+    /// Loading the program would overwrite an instruction address already
+    /// used by another program.
+    AddressInUse(usize),
 }
 
 impl<'d, PIO: Instance> Common<'d, PIO> {
-    pub fn load_program<const SIZE: usize>(&mut self, prog: &RelocatedProgram<SIZE>) -> LoadedProgram<'d, PIO> {
+    /// Load a PIO program. This will automatically relocate the program to
+    /// an available chunk of free instruction memory if the program origin
+    /// was not explicitly specified, otherwise it will attempt to load the
+    /// program only at its origin.
+    pub fn load_program<const SIZE: usize>(&mut self, prog: &Program<SIZE>) -> LoadedProgram<'d, PIO> {
         match self.try_load_program(prog) {
             Ok(r) => r,
-            Err(at) => panic!("Trying to write already used PIO instruction memory at {}", at),
+            Err(e) => panic!("Failed to load PIO program: {:?}", e),
         }
     }
 
+    /// Load a PIO program. This will automatically relocate the program to
+    /// an available chunk of free instruction memory if the program origin
+    /// was not explicitly specified, otherwise it will attempt to load the
+    /// program only at its origin.
     pub fn try_load_program<const SIZE: usize>(
         &mut self,
-        prog: &RelocatedProgram<SIZE>,
+        prog: &Program<SIZE>,
+    ) -> Result<LoadedProgram<'d, PIO>, LoadError> {
+        match prog.origin {
+            Some(origin) => self
+                .try_load_program_at(prog, origin)
+                .map_err(|a| LoadError::AddressInUse(a)),
+            None => {
+                // naively search for free space, allowing wraparound since
+                // PIO does support that. with only 32 instruction slots it
+                // doesn't make much sense to do anything more fancy.
+                let mut origin = 0;
+                while origin < 32 {
+                    match self.try_load_program_at(prog, origin as _) {
+                        Ok(r) => return Ok(r),
+                        Err(a) => origin = a + 1,
+                    }
+                }
+                Err(LoadError::InsufficientSpace)
+            }
+        }
+    }
+
+    fn try_load_program_at<const SIZE: usize>(
+        &mut self,
+        prog: &Program<SIZE>,
+        origin: u8,
     ) -> Result<LoadedProgram<'d, PIO>, usize> {
+        let prog = RelocatedProgram::new_with_origin(prog, origin);
         let used_memory = self.try_write_instr(prog.origin() as _, prog.code())?;
         Ok(LoadedProgram {
             used_memory,
@@ -760,7 +804,7 @@ impl<'d, PIO: Instance> Common<'d, PIO> {
         })
     }
 
-    pub fn try_write_instr<I>(&mut self, start: usize, instrs: I) -> Result<InstanceMemory<'d, PIO>, usize>
+    fn try_write_instr<I>(&mut self, start: usize, instrs: I) -> Result<InstanceMemory<'d, PIO>, usize>
     where
         I: Iterator<Item = u16>,
     {
diff --git a/embassy-rp/src/relocate.rs b/embassy-rp/src/relocate.rs
index 9cb279ccd..b35b4ed72 100644
--- a/embassy-rp/src/relocate.rs
+++ b/embassy-rp/src/relocate.rs
@@ -41,11 +41,6 @@ pub struct RelocatedProgram<'a, const PROGRAM_SIZE: usize> {
 }
 
 impl<'a, const PROGRAM_SIZE: usize> RelocatedProgram<'a, PROGRAM_SIZE> {
-    pub fn new(program: &Program<PROGRAM_SIZE>) -> RelocatedProgram<PROGRAM_SIZE> {
-        let origin = program.origin.unwrap_or(0);
-        RelocatedProgram { program, origin }
-    }
-
     pub fn new_with_origin(program: &Program<PROGRAM_SIZE>, origin: u8) -> RelocatedProgram<PROGRAM_SIZE> {
         RelocatedProgram { program, origin }
     }
diff --git a/examples/rp/src/bin/pio_async.rs b/examples/rp/src/bin/pio_async.rs
index c001d6440..a6d6144be 100644
--- a/examples/rp/src/bin/pio_async.rs
+++ b/examples/rp/src/bin/pio_async.rs
@@ -8,7 +8,6 @@ use embassy_executor::Spawner;
 use embassy_rp::bind_interrupts;
 use embassy_rp::peripherals::PIO0;
 use embassy_rp::pio::{Common, Config, InterruptHandler, Irq, Pio, PioPin, ShiftDirection, StateMachine};
-use embassy_rp::relocate::RelocatedProgram;
 use fixed::traits::ToFixed;
 use fixed_macro::types::U56F8;
 use {defmt_rtt as _, panic_probe as _};
@@ -29,9 +28,8 @@ fn setup_pio_task_sm0<'a>(pio: &mut Common<'a, PIO0>, sm: &mut StateMachine<'a,
         ".wrap",
     );
 
-    let relocated = RelocatedProgram::new(&prg.program);
     let mut cfg = Config::default();
-    cfg.use_program(&pio.load_program(&relocated), &[]);
+    cfg.use_program(&pio.load_program(&prg.program), &[]);
     let out_pin = pio.make_pio_pin(pin);
     cfg.set_out_pins(&[&out_pin]);
     cfg.set_set_pins(&[&out_pin]);
@@ -65,9 +63,8 @@ fn setup_pio_task_sm1<'a>(pio: &mut Common<'a, PIO0>, sm: &mut StateMachine<'a,
         ".wrap",
     );
 
-    let relocated = RelocatedProgram::new(&prg.program);
     let mut cfg = Config::default();
-    cfg.use_program(&pio.load_program(&relocated), &[]);
+    cfg.use_program(&pio.load_program(&prg.program), &[]);
     cfg.clock_divider = (U56F8!(125_000_000) / 2000).to_fixed();
     cfg.shift_in.auto_fill = true;
     cfg.shift_in.direction = ShiftDirection::Right;
@@ -96,9 +93,8 @@ fn setup_pio_task_sm2<'a>(pio: &mut Common<'a, PIO0>, sm: &mut StateMachine<'a,
         "irq 3 [15]",
         ".wrap",
     );
-    let relocated = RelocatedProgram::new(&prg.program);
     let mut cfg = Config::default();
-    cfg.use_program(&pio.load_program(&relocated), &[]);
+    cfg.use_program(&pio.load_program(&prg.program), &[]);
     cfg.clock_divider = (U56F8!(125_000_000) / 2000).to_fixed();
     sm.set_config(&cfg);
 }
diff --git a/examples/rp/src/bin/pio_dma.rs b/examples/rp/src/bin/pio_dma.rs
index 9ab72e1f3..86e5017ac 100644
--- a/examples/rp/src/bin/pio_dma.rs
+++ b/examples/rp/src/bin/pio_dma.rs
@@ -8,7 +8,6 @@ use embassy_executor::Spawner;
 use embassy_futures::join::join;
 use embassy_rp::peripherals::PIO0;
 use embassy_rp::pio::{Config, InterruptHandler, Pio, ShiftConfig, ShiftDirection};
-use embassy_rp::relocate::RelocatedProgram;
 use embassy_rp::{bind_interrupts, Peripheral};
 use fixed::traits::ToFixed;
 use fixed_macro::types::U56F8;
@@ -46,9 +45,8 @@ async fn main(_spawner: Spawner) {
         ".wrap",
     );
 
-    let relocated = RelocatedProgram::new(&prg.program);
     let mut cfg = Config::default();
-    cfg.use_program(&common.load_program(&relocated), &[]);
+    cfg.use_program(&common.load_program(&prg.program), &[]);
     cfg.clock_divider = (U56F8!(125_000_000) / U56F8!(10_000)).to_fixed();
     cfg.shift_in = ShiftConfig {
         auto_fill: true,
diff --git a/examples/rp/src/bin/pio_hd44780.rs b/examples/rp/src/bin/pio_hd44780.rs
index 8aedd24b6..d80c5c24b 100644
--- a/examples/rp/src/bin/pio_hd44780.rs
+++ b/examples/rp/src/bin/pio_hd44780.rs
@@ -14,7 +14,6 @@ use embassy_rp::pio::{
     Config, Direction, FifoJoin, InterruptHandler, Pio, PioPin, ShiftConfig, ShiftDirection, StateMachine,
 };
 use embassy_rp::pwm::{self, Pwm};
-use embassy_rp::relocate::RelocatedProgram;
 use embassy_rp::{bind_interrupts, into_ref, Peripheral, PeripheralRef};
 use embassy_time::{Duration, Instant, Timer};
 use {defmt_rtt as _, panic_probe as _};
@@ -127,9 +126,8 @@ impl<'l> HD44780<'l> {
 
         sm0.set_pin_dirs(Direction::Out, &[&rs, &rw, &e, &db4, &db5, &db6, &db7]);
 
-        let relocated = RelocatedProgram::new(&prg.program);
         let mut cfg = Config::default();
-        cfg.use_program(&common.load_program(&relocated), &[&e]);
+        cfg.use_program(&common.load_program(&prg.program), &[&e]);
         cfg.clock_divider = 125u8.into();
         cfg.set_out_pins(&[&db4, &db5, &db6, &db7]);
         cfg.shift_out = ShiftConfig {
@@ -201,9 +199,8 @@ impl<'l> HD44780<'l> {
             "#
         );
 
-        let relocated = RelocatedProgram::new(&prg.program);
         let mut cfg = Config::default();
-        cfg.use_program(&common.load_program(&relocated), &[&e]);
+        cfg.use_program(&common.load_program(&prg.program), &[&e]);
         cfg.clock_divider = 8u8.into(); // ~64ns/insn
         cfg.set_jmp_pin(&db7);
         cfg.set_set_pins(&[&rs, &rw]);
diff --git a/examples/rp/src/bin/pio_uart.rs b/examples/rp/src/bin/pio_uart.rs
index ca1c7f394..5fddbe292 100644
--- a/examples/rp/src/bin/pio_uart.rs
+++ b/examples/rp/src/bin/pio_uart.rs
@@ -222,8 +222,8 @@ mod uart {
                 mut common, sm0, sm1, ..
             } = Pio::new(pio, Irqs);
 
-            let (tx, origin) = PioUartTx::new(&mut common, sm0, tx_pin, baud, None);
-            let (rx, _) = PioUartRx::new(&mut common, sm1, rx_pin, baud, Some(origin));
+            let tx = PioUartTx::new(&mut common, sm0, tx_pin, baud);
+            let rx = PioUartRx::new(&mut common, sm1, rx_pin, baud);
 
             PioUart { tx, rx }
         }
@@ -240,7 +240,6 @@ mod uart_tx {
     use embassy_rp::gpio::Level;
     use embassy_rp::peripherals::PIO0;
     use embassy_rp::pio::{Common, Config, Direction, FifoJoin, PioPin, ShiftDirection, StateMachine};
-    use embassy_rp::relocate::RelocatedProgram;
     use embedded_io::asynch::Write;
     use embedded_io::Io;
     use fixed::traits::ToFixed;
@@ -256,9 +255,8 @@ mod uart_tx {
             mut sm_tx: StateMachine<'a, PIO0, 0>,
             tx_pin: impl PioPin,
             baud: u64,
-            origin: Option<u8>,
-        ) -> (Self, u8) {
-            let mut prg = pio_proc::pio_asm!(
+        ) -> Self {
+            let prg = pio_proc::pio_asm!(
                 r#"
                 .side_set 1 opt
 
@@ -272,17 +270,14 @@ mod uart_tx {
                     jmp x-- bitloop   [6]  ; Each loop iteration is 8 cycles.
             "#
             );
-            prg.program.origin = origin;
             let tx_pin = common.make_pio_pin(tx_pin);
             sm_tx.set_pins(Level::High, &[&tx_pin]);
             sm_tx.set_pin_dirs(Direction::Out, &[&tx_pin]);
 
-            let relocated = RelocatedProgram::new(&prg.program);
-
             let mut cfg = Config::default();
 
             cfg.set_out_pins(&[&tx_pin]);
-            cfg.use_program(&common.load_program(&relocated), &[&tx_pin]);
+            cfg.use_program(&common.load_program(&prg.program), &[&tx_pin]);
             cfg.shift_out.auto_fill = false;
             cfg.shift_out.direction = ShiftDirection::Right;
             cfg.fifo_join = FifoJoin::TxOnly;
@@ -290,18 +285,7 @@ mod uart_tx {
             sm_tx.set_config(&cfg);
             sm_tx.set_enable(true);
 
-            // The 4 state machines of the PIO each have their own program counter that starts taking
-            // instructions at an offset (origin) of the 32 instruction "space" the PIO device has.
-            // It is up to the programmer to sort out where to place these instructions.
-            // From the pio_asm! macro you get a ProgramWithDefines which has a field .program.origin
-            // which takes an Option<u8>.
-            //
-            // When you load more than one RelocatedProgram into the PIO,
-            // you load your first program at origin = 0.
-            // The RelocatedProgram has .code().count() which returns a usize,
-            // for which you can then use as your next program's origin.
-            let offset = relocated.code().count() as u8 + origin.unwrap_or_default();
-            (Self { sm_tx }, offset)
+            Self { sm_tx }
         }
 
         pub async fn write_u8(&mut self, data: u8) {
@@ -329,7 +313,6 @@ mod uart_rx {
     use embassy_rp::gpio::Level;
     use embassy_rp::peripherals::PIO0;
     use embassy_rp::pio::{Common, Config, Direction, FifoJoin, PioPin, ShiftDirection, StateMachine};
-    use embassy_rp::relocate::RelocatedProgram;
     use embedded_io::asynch::Read;
     use embedded_io::Io;
     use fixed::traits::ToFixed;
@@ -345,9 +328,8 @@ mod uart_rx {
             mut sm_rx: StateMachine<'a, PIO0, 1>,
             rx_pin: impl PioPin,
             baud: u64,
-            origin: Option<u8>,
-        ) -> (Self, u8) {
-            let mut prg = pio_proc::pio_asm!(
+        ) -> Self {
+            let prg = pio_proc::pio_asm!(
                 r#"
                 ; Slightly more fleshed-out 8n1 UART receiver which handles framing errors and
                 ; break conditions more gracefully.
@@ -369,10 +351,8 @@ mod uart_rx {
                     push                ; important in case the TX clock is slightly too fast.
             "#
             );
-            prg.program.origin = origin;
-            let relocated = RelocatedProgram::new(&prg.program);
             let mut cfg = Config::default();
-            cfg.use_program(&common.load_program(&relocated), &[]);
+            cfg.use_program(&common.load_program(&prg.program), &[]);
 
             let rx_pin = common.make_pio_pin(rx_pin);
             sm_rx.set_pins(Level::High, &[&rx_pin]);
@@ -387,8 +367,7 @@ mod uart_rx {
             sm_rx.set_config(&cfg);
             sm_rx.set_enable(true);
 
-            let offset = relocated.code().count() as u8 + origin.unwrap_or_default();
-            (Self { sm_rx }, offset)
+            Self { sm_rx }
         }
 
         pub async fn read_u8(&mut self) -> u8 {
diff --git a/examples/rp/src/bin/pio_ws2812.rs b/examples/rp/src/bin/pio_ws2812.rs
index 3de2bd48d..bc87016ec 100644
--- a/examples/rp/src/bin/pio_ws2812.rs
+++ b/examples/rp/src/bin/pio_ws2812.rs
@@ -12,7 +12,6 @@ use embassy_rp::peripherals::PIO0;
 use embassy_rp::pio::{
     Common, Config, FifoJoin, Instance, InterruptHandler, Pio, PioPin, ShiftConfig, ShiftDirection, StateMachine,
 };
-use embassy_rp::relocate::RelocatedProgram;
 use embassy_rp::{bind_interrupts, clocks, into_ref, Peripheral, PeripheralRef};
 use embassy_time::{Duration, Timer};
 use fixed::types::U24F8;
@@ -73,8 +72,7 @@ impl<'d, P: Instance, const S: usize, const N: usize> Ws2812<'d, P, S, N> {
         cfg.set_out_pins(&[&out_pin]);
         cfg.set_set_pins(&[&out_pin]);
 
-        let relocated = RelocatedProgram::new(&prg);
-        cfg.use_program(&pio.load_program(&relocated), &[&out_pin]);
+        cfg.use_program(&pio.load_program(&prg), &[&out_pin]);
 
         // Clock config, measured in kHz to avoid overflows
         // TODO CLOCK_FREQ should come from embassy_rp
diff --git a/tests/rp/src/bin/pio_irq.rs b/tests/rp/src/bin/pio_irq.rs
index 45004424a..bdea63eaa 100644
--- a/tests/rp/src/bin/pio_irq.rs
+++ b/tests/rp/src/bin/pio_irq.rs
@@ -9,7 +9,6 @@ use embassy_executor::Spawner;
 use embassy_rp::bind_interrupts;
 use embassy_rp::peripherals::PIO0;
 use embassy_rp::pio::{Config, InterruptHandler, Pio};
-use embassy_rp::relocate::RelocatedProgram;
 use {defmt_rtt as _, panic_probe as _};
 
 bind_interrupts!(struct Irqs {
@@ -35,9 +34,8 @@ async fn main(_spawner: Spawner) {
         "irq wait 1",
     );
 
-    let relocated = RelocatedProgram::new(&prg.program);
     let mut cfg = Config::default();
-    cfg.use_program(&common.load_program(&relocated), &[]);
+    cfg.use_program(&common.load_program(&prg.program), &[]);
     sm.set_config(&cfg);
     sm.set_enable(true);
 
diff --git a/tests/rp/src/bin/pio_multi_load.rs b/tests/rp/src/bin/pio_multi_load.rs
new file mode 100644
index 000000000..356f16795
--- /dev/null
+++ b/tests/rp/src/bin/pio_multi_load.rs
@@ -0,0 +1,126 @@
+#![no_std]
+#![no_main]
+#![feature(type_alias_impl_trait)]
+#[path = "../common.rs"]
+mod common;
+
+use defmt::info;
+use embassy_executor::Spawner;
+use embassy_rp::bind_interrupts;
+use embassy_rp::peripherals::PIO0;
+use embassy_rp::pio::{Config, InterruptHandler, LoadError, Pio};
+use {defmt_rtt as _, panic_probe as _};
+
+bind_interrupts!(struct Irqs {
+    PIO0_IRQ_0 => InterruptHandler<PIO0>;
+});
+
+#[embassy_executor::main]
+async fn main(_spawner: Spawner) {
+    let p = embassy_rp::init(Default::default());
+    let pio = p.PIO0;
+    let Pio {
+        mut common,
+        mut sm0,
+        mut sm1,
+        mut sm2,
+        irq_flags,
+        ..
+    } = Pio::new(pio, Irqs);
+
+    // load with explicit origin works
+    let prg1 = pio_proc::pio_asm!(
+        ".origin 4"
+        "nop",
+        "nop",
+        "nop",
+        "nop",
+        "nop",
+        "nop",
+        "nop",
+        "irq 0",
+        "nop",
+        "nop",
+    );
+    let loaded1 = common.load_program(&prg1.program);
+    assert_eq!(loaded1.origin, 4);
+    assert_eq!(loaded1.wrap.source, 13);
+    assert_eq!(loaded1.wrap.target, 4);
+
+    // load without origin chooses a free space
+    let prg2 = pio_proc::pio_asm!("nop", "nop", "nop", "nop", "nop", "nop", "nop", "irq 1", "nop", "nop",);
+    let loaded2 = common.load_program(&prg2.program);
+    assert_eq!(loaded2.origin, 14);
+    assert_eq!(loaded2.wrap.source, 23);
+    assert_eq!(loaded2.wrap.target, 14);
+
+    // wrapping around the end of program space automatically works
+    let prg3 =
+        pio_proc::pio_asm!("nop", "nop", "nop", "nop", "nop", "nop", "nop", "nop", "nop", "nop", "nop", "irq 2",);
+    let loaded3 = common.load_program(&prg3.program);
+    assert_eq!(loaded3.origin, 24);
+    assert_eq!(loaded3.wrap.source, 3);
+    assert_eq!(loaded3.wrap.target, 24);
+
+    // check that the programs actually work
+    {
+        let mut cfg = Config::default();
+        cfg.use_program(&loaded1, &[]);
+        sm0.set_config(&cfg);
+        sm0.set_enable(true);
+        while !irq_flags.check(0) {}
+        sm0.set_enable(false);
+    }
+    {
+        let mut cfg = Config::default();
+        cfg.use_program(&loaded2, &[]);
+        sm1.set_config(&cfg);
+        sm1.set_enable(true);
+        while !irq_flags.check(1) {}
+        sm1.set_enable(false);
+    }
+    {
+        let mut cfg = Config::default();
+        cfg.use_program(&loaded3, &[]);
+        sm2.set_config(&cfg);
+        sm2.set_enable(true);
+        while !irq_flags.check(2) {}
+        sm2.set_enable(false);
+    }
+
+    // instruction memory is full now. all loads should fail.
+    {
+        let prg = pio_proc::pio_asm!(".origin 0", "nop");
+        match common.try_load_program(&prg.program) {
+            Err(LoadError::AddressInUse(0)) => (),
+            _ => panic!("program loaded when it shouldn't"),
+        };
+
+        let prg = pio_proc::pio_asm!("nop");
+        match common.try_load_program(&prg.program) {
+            Err(LoadError::InsufficientSpace) => (),
+            _ => panic!("program loaded when it shouldn't"),
+        };
+    }
+
+    // freeing some memory should allow further loads though.
+    unsafe {
+        common.free_instr(loaded3.used_memory);
+    }
+    {
+        let prg = pio_proc::pio_asm!(".origin 0", "nop");
+        match common.try_load_program(&prg.program) {
+            Ok(_) => (),
+            _ => panic!("program didn't loaded when it shouldn"),
+        };
+
+        let prg = pio_proc::pio_asm!("nop");
+        match common.try_load_program(&prg.program) {
+            Ok(_) => (),
+            _ => panic!("program didn't loaded when it shouldn"),
+        };
+    }
+
+    info!("Test OK");
+    cortex_m::asm::bkpt();
+}