//
// Copyright (c) Zach Marcantel. All rights reserved.
// Licensed under the GPLv3. See LICENSE file in the project root
// for full license information.
//

#![no_std]

/// Generate a unit structure to represent a set of bit-regions.
/// Intended to be used both as bitflags held in structs/collections as well
/// as representing something like a memory-mapped register in more embedded
/// applications.
///
/// This crate is set as `#![no_std]` so it can freely be used in other such crates.
///
/// Regions are given the `#repr({type})` attribute based on the `{repr}`
/// given to the macro.
///
/// The following traits are generated for the new struct:
/// - `Into<{repr}>`
/// - `From<{repr}>`
/// - `PartialEq`
/// - `Display`
///     - toggles print their name if set
///     - multibit always prints `{name}={val}`
/// - `Debug`
///     - prints raw value in hex
/// - `+` and `+=`
/// - `-` and `-=`
/// - `*` and `*=`
/// - `/` and `/=`
/// - `^` and `^=`
/// - `|` and `|=`
/// - `&` and `&=`
///
/// # Basic Example:
///
/// Example purely to show the API.
/// Creates a stack-based u16 unit-struct with helper methods.
///
/// ```
/// # #[macro_use] extern crate bitregions;
/// bitregions! {
///     pub Example u16 {
///         EN_FEATURE:   0b0000000000000001,
///         EN_DEVICE:    0b0000000000000010,
///         PORT_NUM:     0b0000000000011100 | 0..=5, // only 0-5 is valid
///         BUSY:         0b0000000001000000,
///         VAL_BUFFER:   0b1111111100000000,
///     }
///
///     pub fn port_and_value(port: u8, val: u8) -> Example {
///         let mut r = Example::new(0u16);
///         r.set_port_num(port);
///         r.set_val_buffer(val);
///         r
///     }
/// }
///
/// fn main() {
///     println!("value buffer mask is: {:#X}", Example::VAL_BUFFER);
///
///     // create an example memory mapped io register
///     // exists on the stack with the value 0.
///     // see below for using this as a pointer to the register.
///     let mut ex = Example::new(0u16);
///
///     // enable the feature this register governs
///     ex.set_en_feature();
///
///     // wait for the busy bit to clear
///     // then set busy to block reader (could be more pedantic with ex.set_busy())
///     while ex.busy() { println!("bus is busy"); }
///     ex.toggle_busy();
///     assert_eq!(ex.extract_busy().raw() & Example::BUSY, Example::BUSY);
///
///     // set the port to write to. must be 0-5
///     // otherwise we trigger a debug_assert! (removed in release builds)
///     // same with the value buffer
///     ex |= Example::port_and_value(4u8, 0x38u8);
///     // clear busy bit (could be more pedantic with ex.unset_busy())
///     ex.toggle_busy();
///
///     // wait for a response
///     while ex.busy() { println!("waiting for response"); }
///
///     // read the value out of the buffer (pre-shifted for you)
///     // then, assert the shift happened correctly by looking at the
///     // unshifted version returned by the extract_{field} variant.
///     let resp = ex.val_buffer() as u16;
///     assert_eq!(resp << 8, ex.extract_val_buffer().raw());
///
///     // disable the feature this register governs
///     ex.unset_en_feature();
///
///
///     //
///     // math and bitwise operations
///     //
///
///     ex += 1u16;
///     ex -= 1u16;
///     ex *= 2u16;
///     ex /= 2u16;
///     ex |= 0xBDu8;
///     ex &= 0xDBu8;
///     ex ^= ex;
///
///     //
///     // display and debug
///     //
///
///     ex = Example::with_en_feature(); // use a with_{field} ctor
///     ex.set_port_num(4u8);
///     ex.set_val_buffer(0xABu8);
///     let display = format!("{}", ex);
///     assert_eq!(display, "EN_FEATURE | PORT_NUM=0x4 | VAL_BUFFER=0xAB");
///
///     let debug = format!("{:?}", ex);
///     assert_eq!(debug, "0xAB11");
///
///
///     //
///     // get region as a tuple
///     //
///
///     // as a tuple of u8 e.g. (u8, u8, u8) for port_num
///     let tup = ex.port_num_tuple();
///     assert_eq!(
///         ex.port_num(),
///         match tup {
///             (0,0,0) => { 0 }
///             (0,0,1) => { 1 }
///             (0,1,0) => { 2 }
///             (0,1,1) => { 3 }
///             (1,0,0) => { 4 }
///             (1,0,1) => { 5 }
///             _ => { 0xFF }
///         },
///         "got {:?}, but expected {:b}", tup, ex.port_num(),
///     );
///
///     // or as a tuple of booleans e.g. (bool, bool, bool) for port_num
///     let bools = ex.port_num_bools();
///     if bools.1 {
///         // the second bit in the port number is set
///     }
/// }
/// ```
///
/// # Memory-mapped Example:
///
/// A common case for bitmaps/bitflags/etc are memory-mapped registers.
/// Below is an example that creates a lifetimed reference to some memory
/// region this register would represent.
///
/// You can optionally provide a default address location using the
/// `{name} {repr} @ {addr}` syntax. This variant returns a static, mutable ref.
///
/// ```
/// # #[macro_use] extern crate bitregions;
/// bitregions! {
///     pub Example u16 @ 0xDEADBEEF {
///         EN_FEATURE:   0b0000000000000001,
///         EN_DEVICE:    0b0000000000000010,
///         PORT_NUM:     0b0000000000011100 | 0..=5, // only 0-5 is valid
///         BUSY:         0b0000000001000000,
///         VAL_BUFFER:   0b1111111100000000,
///     }
/// }
///
/// const MEMIO_ADDR: usize = 0xC0FFEE;
/// bitregions! {
///     pub MemIOBase u16 @ MEMIO_ADDR {
///         SOME_REGION:  0b0000000000000001,
///     }
/// }
/// bitregions! {
///     pub ControlReg u16 @ MEMIO_ADDR + 0x80 {
///         SOME_REGION:  0b0000000000000001,
///     }
/// }
///
///
/// fn main() {
///     // create "fake memory" so the doc-test works
///     // address is the important thing
///     let mem: [u8; 4096] = [0u8; 4096];
///
///     // create a lifetimed reference to the register elsewhere
///     // in memory (the above slice, in our case, but could be anywhere)
///     let ex = unsafe { Example::at_addr_mut(&mem[8] as *const _ as usize) };
///
///     // everything else works like normal
///     ex.set_en_feature();
///     assert!(ex.en_feature());
///     ex.set_val_buffer(128u8);
///     println!("{:#X}", ex.val_buffer());
///     assert_eq!(128, ex.val_buffer());
///
///     // you can also initialize the pointer directly
///     let ptr = unsafe { Example::default_ptr() };
///     assert_eq!(ptr as *mut _ as usize, 0xDEADBEEF);
///     // but we cannot use it in the examples or it will segfault :/
///
///     // you can set the default address using a literal, ident, or const expression
///     let memio = unsafe { MemIOBase::default_ptr() };
///     assert_eq!(memio as *mut _ as usize, MEMIO_ADDR);
///     let control = unsafe { ControlReg::default_ptr() };
///     assert_eq!(control as *mut _ as usize, MEMIO_ADDR + 0x80);
/// }
/// ```
///
/// # From Reference Example:
///
/// Below is an example which casts a reference of the region's underlying
/// type to our generated struct. This allows you to "add features" to a raw
/// value. While safer than the memory-mapped example but is still unsafe code
/// as you could share a reference into a slice.
///
/// ```
/// # #[macro_use] extern crate bitregions;
/// bitregions! {
///     pub Example u16 {
///         EN_FEATURE:   0b0000000000000001,
///         EN_DEVICE:    0b0000000000000010,
///         PORT_NUM:     0b0000000000011100 | 0..=5, // only 0-5 is valid
///         BUSY:         0b0000000001000000,
///         VAL_BUFFER:   0b1111111100000000,
///     }
/// }
///
///
/// fn main() {
///     // create "fake memory" to illustrate the example
///     // the reference could be to a single u16 or relevant type...
///     let mut mem: [u8; 4096] = [0u8; 4096];
///
///     // create the reference -- this is unsafe because we allow
///     // for a wider range of types than strictly the underlying type.
///     // you can see in this example we use a &u8 to create (effectively) a &u16
///     let ex = unsafe { Example::at_ref_mut(&mut mem[8]) };
///
///     // everything else works like normal
///     ex.set_en_feature();
///     assert!(ex.en_feature());
///     ex.set_val_buffer(128u8);
///     println!("{:#X}", ex.val_buffer());
///     assert_eq!(128, ex.val_buffer());
/// }
/// ```
///
///
/// # Debug Assertions
///
/// When built in debug-mode, setters will assert the given value
/// both fits in the region (4bit number in 2bit region) and is within
/// the (optional) range (3bit region, 0-5 allowed, given 7).
///
/// ```should_panic
/// # #[macro_use] extern crate bitregions;
/// bitregions! {
///     pub Example u8 {
///         RANGED:     0b00011100 | 1..=6,
///         NON_RANGED: 0b11100000,
///     }
/// }
///
///
/// fn main() {
///     let mut ex = Example::new(0u8);
///
///     ex.set_ranged(1u8); // works fine
///     ex.set_ranged(3u8); // works fine
///     ex.set_ranged(6u8); // works fine
///     ex.set_ranged(0u8); // will panic do to range violation
///     ex.set_ranged(7u8); // will panic do to range violation
///     ex.set_ranged(8u8); // will panic do to region violation
///
///     ex.set_non_ranged(1u8); // works fine
///     ex.set_non_ranged(3u8); // works fine
///     ex.set_non_ranged(6u8); // works fine
///     ex.set_non_ranged(0u8); // works fine
///     ex.set_non_ranged(7u8); // works fine
///     ex.set_non_ranged(8u8); // will panic do to region violation
/// }
/// ```
///
pub use bitregions_impl::bitregions;

#[cfg(test)]
mod test {
    use super::*;

    bitregions! {
        pub Test u16 {
            LOW_REGION:     0b00000111 | 0..=5,
            HIGH_REGION:    0b00011000,
            HIGH_TOGGLE:    0b01000000,
        }


        pub fn with_regions(high: u8, low: u8) -> Test {
            let mut r = Test::new(0u16);
            r.set_high_region(high);
            r.set_low_region(low);
            r
        }
    }

    bitregions! {
        pub DefaultLitAddrTest u16 @ 0xC0FFEE {
            HIGH_TOGGLE:    0b01000000,
        }
    }

    const DEFAULT_ADDR_CONST: usize = 0xDEADBEEF;
    bitregions! {
        pub DefaultConstAddrTest u16 @ DEFAULT_ADDR_CONST {
            HIGH_TOGGLE:    0b01000000,
        }
    }

    bitregions! {
        pub DefaultExprAddrTest u16 @ DEFAULT_ADDR_CONST + 0x80 {
            HIGH_TOGGLE:    0b01000000,
        }
    }

    bitregions! {
        pub WideRegionTest u32 @ DEFAULT_ADDR_CONST + 0x80 {
            BITS6:     0b00000000000000000000000000111111,
            BITS10:    0b00000000000000011111111110000000,
            BITS15:    0b11111111111111100000000000000000,
        }
    }

    // TODO: test overlap funcs
    // TODO: should_panic tests around generation?
    /*
    bitregions! {
        pub TestOverlap u16 {
            LOW_REGION:     0b00000111,
            HIGH_REGION:    0b00011100,
        }
    }
    */


    // TODO: test gaps funcs
    // TODO: should_panic tests around generation?
    /*
    bitregions! {
        pub TestGap u16 {
            GAP:    0b00101000,
        }
    }
    bitregions! {
        pub TestMultGap u16 {
            GAP:    0b00101010,
        }
    }
    */

    #[test]
    fn default_impl() {
        assert_eq!(Test::default().raw(), 0);
        assert_eq!(DefaultLitAddrTest::default().raw(), 0);
        assert_eq!(DefaultConstAddrTest::default().raw(), 0);
        assert_eq!(DefaultExprAddrTest::default().raw(), 0);
        assert_eq!(WideRegionTest::default().raw(), 0);
    }

    #[test]
    fn with_ctors() {
        assert_eq!(Test::with_high_toggle(), Test::HIGH_TOGGLE.into());
        assert_eq!(Test::with_low_region(4u8), Test::new(4u16));
        assert_eq!(Test::with_high_region(3u8), Test::new(3u16 << 3));
    }

    #[test]
    fn user_fns() {
        let mut expect = Test::new(0u16);
        expect.set_low_region(4u8);
        expect.set_high_region(3u8);
        assert_eq!(expect, Test::with_regions(3, 4));
    }

    #[test]
    fn get_set_low_region() {
        let mut test = Test::from(0);

        assert!(0 == test.low_region());
        test.set_low_region(5u8);
        assert!(5 == test.low_region());
        test.set_low_region(2u8);
        assert!(2 == test.low_region());
        test.set_low_region(4u8);
        assert!(4 == test.low_region());
        test.set_low_region(0u8);
        assert!(0 == test.low_region());
    }

    #[test]
    fn get_low_region_tuple() {
        let mut test = Test::with_low_region(5u8);

        let mut tup = test.low_region_tuple();
        assert_eq!(tup, (1,0,1));

        test.set_low_region(1u8);
        tup = test.low_region_tuple();
        assert_eq!(tup, (0,0,1));

        test.set_low_region(4u8);
        tup = test.low_region_tuple();
        assert_eq!(tup, (1,0,0));
    }

    #[test]
    fn get_low_region_bools() {
        let mut test = Test::with_low_region(5u8);

        let mut bools = test.low_region_bools();
        assert_eq!(bools, (true,false,true));

        test.set_low_region(1u8);
        bools = test.low_region_bools();
        assert_eq!(bools, (false,false,true));

        test.set_low_region(4u8);
        bools = test.low_region_bools();
        assert_eq!(bools, (true,false,false));
    }

    #[test]
    #[should_panic]
    fn set_beyond_low_region() {
        let mut test = Test::from(0);
        test.set_low_region(8u8);
    }

    #[test]
    #[should_panic]
    fn set_low_region_outside_range() {
        let mut test = Test::from(0);
        test.set_low_region(6u8);
    }

    #[test]
    fn get_set_high_region() {
        let mut test = Test::from(0);

        assert!(0 == test.high_region());
        test.set_high_region(2u8);
        assert!(2 == test.high_region());
        test.set_low_region(3u8);
        assert!(3 == test.low_region());
        test.set_high_region(0u8);
        assert!(0 == test.high_region());
    }

    #[test]
    fn get_high_region_tuple() {
        let mut test = Test::with_high_region(1u8);

        let mut tup = test.high_region_tuple();
        assert_eq!(tup, (0,1));

        test.set_high_region(3u8);
        tup = test.high_region_tuple();
        assert_eq!(tup, (1,1));

        test.set_high_region(0u8);
        tup = test.high_region_tuple();
        assert_eq!(tup, (0,0));
    }

    #[test]
    fn get_high_region_bools() {
        let mut test = Test::with_high_region(1u8);

        let mut bools = test.high_region_bools();
        assert_eq!(bools, (false,true));

        test.set_high_region(3u8);
        bools = test.high_region_bools();
        assert_eq!(bools, (true,true));

        test.set_high_region(0u8);
        bools = test.high_region_bools();
        assert_eq!(bools, (false,false));
    }

    #[test]
    #[should_panic]
    fn set_beyond_high_region() {
        let mut test = Test::from(0);
        test.set_high_region(4u8);
    }

    #[test]
    fn toggle() {
        let mut test = Test::from(0);

        assert!(!test.high_toggle());
        test.toggle_high_toggle();
        assert!(test.high_toggle());
        test.toggle_high_toggle();
        assert!(!test.high_toggle());
    }

    #[test]
    fn set_single_bit() {
        let mut test = Test::from(0);

        assert!(!test.high_toggle());
        test.set_high_toggle();
        assert!(test.high_toggle());
        test.set_high_toggle();
        assert!(test.high_toggle());
    }

    #[test]
    fn unset_single_bit() {
        let mut test = Test::from(0);

        assert!(!test.high_toggle());
        test.set_high_toggle();
        assert!(test.high_toggle());
        test.unset_high_toggle();
        assert!(!test.high_toggle());
        test.unset_high_toggle();
        assert!(!test.high_toggle());
    }

    #[test]
    fn at_addr() {
        let mut mem: [u8; 4096] = [0u8; 4096];
        let u16_ptr = &mut mem[8] as *mut _ as *mut u16;
        let test = unsafe {
            Test::at_addr_mut(&mut mem[8] as *mut _ as usize)
        };

        assert_eq!(unsafe{*u16_ptr}, 0);
        assert_eq!(unsafe{*u16_ptr}, test.raw());

        test.set_high_region(3u8);
        assert_eq!(unsafe{*u16_ptr}, 0b11000);
        assert_eq!(unsafe{*u16_ptr}, test.raw());

        test.set_low_region(5u8);
        assert_eq!(unsafe{*u16_ptr}, 0b11101);
        assert_eq!(unsafe{*u16_ptr}, test.raw());

        test.toggle_high_toggle();
        assert_eq!(unsafe{*u16_ptr}, 0b1011101);
        assert_eq!(unsafe{*u16_ptr}, test.raw());

        test.toggle_high_toggle();
        assert_eq!(unsafe{*u16_ptr}, 0b0011101);
        assert_eq!(unsafe{*u16_ptr}, test.raw());
    }

    #[test]
    fn at_ref() {
        let mut mem: [u8; 4096] = [0u8; 4096];
        let u16_ptr = &mut mem[16] as *mut _ as *mut u16;
        let test = unsafe { Test::at_ref_mut(&mut mem[16]) };

        assert_eq!(unsafe{*u16_ptr}, 0);
        assert_eq!(unsafe{*u16_ptr}, test.raw());

        test.set_high_region(3u8);
        assert_eq!(unsafe{*u16_ptr}, 0b11000);
        assert_eq!(unsafe{*u16_ptr}, test.raw());

        test.set_low_region(5u8);
        assert_eq!(unsafe{*u16_ptr}, 0b11101);
        assert_eq!(unsafe{*u16_ptr}, test.raw());

        test.toggle_high_toggle();
        assert_eq!(unsafe{*u16_ptr}, 0b1011101);
        assert_eq!(unsafe{*u16_ptr}, test.raw());

        test.toggle_high_toggle();
        assert_eq!(unsafe{*u16_ptr}, 0b0011101);
        assert_eq!(unsafe{*u16_ptr}, test.raw());
    }

    #[test]
    fn math_ops() {
        // add
        assert_eq!(Test::new(18u16), Test::new(3u16) + Test::new(15u16));
        // sub
        assert_eq!(Test::new(7u16), Test::new(20u16) - Test::new(13u16));
        // mul
        assert_eq!(Test::new(18u16), Test::new(6u16) * Test::new(3u16));
        // div
        assert_eq!(Test::new(3u16), Test::new(24u16) / Test::new(8u16));
    }

    #[test]
    fn math_assign_ops() {
        // add
        let mut add_test = Test::new(3u16);
        add_test += Test::new(15u16);
        assert_eq!(Test::new(18u16), add_test);
        // sub
        let mut sub_test = Test::new(20u16);
        sub_test -= Test::new(13u16);
        assert_eq!(Test::new(7u16), sub_test);
        // mul
        let mut mul_test = Test::new(6u16);
        mul_test *= Test::new(3u16);
        assert_eq!(Test::new(18u16), mul_test);
        // div
        let mut div_test = Test::new(24u16);
        div_test /= Test::new(8u16);
        assert_eq!(Test::new(3u16), div_test);
    }


    #[test]
    fn bit_ops() {
        // or
        assert_eq!(Test::new(0xB4u16), Test::new(0xB0u16) | Test::new(0x04u16));
        // and
        assert_eq!(Test::new(0x04u16), Test::new(0xD7u16) & Test::new(0x04u16));
        // xor
        assert_eq!(Test::new(0b001100u16), Test::new(0b110011u16) ^ Test::new(0b111111u16));
        // shl
        assert_eq!(Test::new(8u16), Test::new(2u16) << Test::new(2u16));
        // shr
        assert_eq!(Test::new(1u16), Test::new(8u16) >> Test::new(3u16));
    }

    #[test]
    fn bit_assign_ops() {
        // or
        let mut or_test = Test::new(0xB0u16);
        or_test |= Test::new(0x04u16);
        assert_eq!(Test::new(0xB4u16), or_test);
        // and
        let mut and_test = Test::new(0xD7u16);
        and_test &= Test::new(0x04u16);
        assert_eq!(Test::new(4u16), and_test);
        // xor
        let mut xor_test = Test::new(0b110011u16);
        xor_test ^= Test::new(0b111111u16);
        assert_eq!(Test::new(0b001100u16), xor_test);
        // shl
        let mut shl_test = Test::new(1u16);
        shl_test <<= Test::new(3u16);
        assert_eq!(Test::new(8u16), shl_test);
        // shr
        let mut shr_test = Test::new(8u16);
        shr_test >>= Test::new(3u16);
        assert_eq!(Test::new(1u16), shr_test);
    }

    #[test]
    fn default_ptr_lit() {
        let ptr = unsafe { DefaultLitAddrTest::default_ptr() };
        assert_eq!(ptr as *mut _ as usize, 0xC0FFEE);
    }

    #[test]
    fn default_ptr_ident() {
        let ptr = unsafe { DefaultConstAddrTest::default_ptr() };
        assert_eq!(ptr as *mut _ as usize, DEFAULT_ADDR_CONST);
    }

    #[test]
    fn default_ptr_expr() {
        let ptr = unsafe { DefaultExprAddrTest::default_ptr() };
        assert_eq!(ptr as *mut _ as usize, DEFAULT_ADDR_CONST + 0x80);
    }

    #[test]
    fn wide_region_getters() {
        let mut test = WideRegionTest::new(0u32);
        test.set_bits6(10u8);
        test.set_bits10(1023u16);
        test.set_bits15(1234u16);

        let bits6: u8 = test.bits6();
        assert_eq!(bits6, 10u8);

        let bits10: u16 = test.bits10();
        assert_eq!(bits10, 1023u16);

        let bits15: u16 = test.bits15();
        assert_eq!(bits15, 1234u16);
    }

    #[test]
    fn wide_region_tuples() {
        let mut test = WideRegionTest::new(0u32);
        test.set_bits6(10u8);
        test.set_bits10(1023u16);
        test.set_bits15(1234u16);

        assert_eq!(test.bits6_tuple(), (0,0,1,0,1,0));
        assert_eq!(test.bits6_bools(), (false,false,true,false,true,false));
    }
}