// ######## necessities

// include guards
#ifndef CH32V003_SPI_H
#define CH32V003_SPI_H

// includes
#include "ch32fun.h"
#include <stdint.h> //uintN_t support

#ifndef APB_CLOCK
#define APB_CLOCK FUNCONF_SYSTEM_CORE_CLOCK
#endif

/*######## library usage and configuration

in the .c files that use this library, you'll need to #define some configuration options _before_ the #include "ch32v003_SPI.h"

SYSTEM_CORE_CLOCK and APB_CLOCK should be defined already as APB_CLOCK is used by this library


#ifndef APB_CLOCK
        #define APB_CLOCK FUNCONF_SYSTEM_CORE_CLOCK
#endif

to enable using the functions of this library:
#define CH32V003_SPI_IMPLEMENTATION

to configure the settings of the SPI bus, first, declare the desired bus speed

#define CH32V003_SPI_SPEED_HZ 1000000

then pick the desired setting of each group:

#define CH32V003_SPI_DIRECTION_2LINE_TXRX
#define CH32V003_SPI_DIRECTION_1LINE_TX

#define CH32V003_SPI_CLK_MODE_POL0_PHA0			//leading = rising		trailing = falling		sample on leading		default if you're unsure
#define CH32V003_SPI_CLK_MODE_POL0_PHA1			//leading = rising		trailing = falling		sample on trailing
#define CH32V003_SPI_CLK_MODE_POL1_PHA0			//leading = falling		trailing = rising		sample on leading
#define CH32V003_SPI_CLK_MODE_POL1_PHA1			//leading = falling		trailing = rising		sample on trailing

#define CH32V003_SPI_NSS_HARDWARE_PC0			// _NSS	toggled by hardware, automatic
#define CH32V003_SPI_NSS_HARDWARE_PC1			// NSS	toggled by hardware, automatic
#define CH32V003_SPI_NSS_SOFTWARE_PC3			// PC3	toggled by software, automatic, manual setters available
#define CH32V003_SPI_NSS_SOFTWARE_PC4			// PC4	toggled by software, automatic, manual setters available
#define CH32V003_SPI_NSS_SOFTWARE_ANY_MANUAL	// toggle manually!
*/

// ######## function overview (declarations): use these!
//  initialize and configure the SPI peripheral
static inline void SPI_init();

// establish / end a connection to the SPI device
static inline void SPI_begin_8();
static inline void SPI_begin_16();
static inline void SPI_end();

// manually set the NSS (chip select) pin high / low
// "SPI_NSS_HIGH_FN" and "SPI_NSS_LOW_FN" only become available functions if the selected NSS is software PC3 or PC4
#if defined(CH32V003_SPI_NSS_SOFTWARE_PC3) || defined(CH32V003_SPI_NSS_SOFTWARE_PC4)
static inline void SPI_NSS_software_low();
static inline void SPI_NSS_software_high();
#endif

// read / write the SPI device
// these commands are raw, you'll have to consider all other steps in SPI_transfer!
static inline uint8_t  SPI_read_8();
static inline uint16_t SPI_read_16();
static inline void     SPI_write_8(uint8_t data);
static inline void     SPI_write_16(uint16_t data);

// send a command and get a response from the SPI device
// you'll use this for most devices
static inline uint8_t  SPI_transfer_8(uint8_t data);
static inline uint16_t SPI_transfer_16(uint16_t data);

// SPI peripheral power enable / disable (default off, init() automatically enables)
// send SPI peripheral to sleep
static inline void SPI_poweroff();
// wake SPI peripheral from sleep
static inline void SPI_poweron();

// helper: kill / restore all interrupts on the CH32V003
static inline void kill_interrrupts();
static inline void restore_interrupts();

// ######## internal function declarations
static inline void    SPI_wait_TX_complete();
static inline uint8_t SPI_is_RX_empty();
static inline void    SPI_wait_RX_available();

// ######## internal variables
static uint16_t EXT1_INTENR_backup;

// ######## preprocessor macros
//  min and max helper macros
#define MIN(a, b) (((a) < (b)) ? (a) : (b))
#define MAX(a, b) (((a) > (b)) ? (a) : (b))

// stringify for displaying what #defines evaluated to at preprocessor stage
#define VALUE_TO_STRING(x) #x
#define VALUE(x) VALUE_TO_STRING(x)
#define VAR_NAME_VALUE(var) #var "=" VALUE(var)

// compile-time log2
#define LOG2(x) ((x) == 0 ? -1 : __builtin_ctz(x))

// compile-time clock prescaler calculation: log2(APB_CLOCK/SPEED_BUS)
#define SPI_CLK_RATIO (APB_CLOCK / CH32V003_SPI_SPEED_HZ)
#define SPI_CLK_PRESCALER LOG2(SPI_CLK_RATIO)

// ensure that CLOCK_PRESCALER_VALUE is within the range of 0..7
_Static_assert(SPI_CLK_PRESCALER >= 0 && SPI_CLK_PRESCALER <= 7, "SPI_CLK_PRESCALER is out of range (0..7). Please set a different SPI bus speed. prescaler = log2(f_CPU/f_SPI)");
// #pragma message(VAR_NAME_VALUE(SPI_CLK_PRESCALER))

// ######## preprocessor #define requirements

#if !defined(CH32V003_SPI_DIRECTION_2LINE_TXRX) && !defined(CH32V003_SPI_DIRECTION_1LINE_TX)
#warning "none of the CH32V003_SPI_DIRECTION_ options were defined!"
#endif
#if defined(CH32V003_SPI_DIRECTION_2LINE_TXRX) && defined(CH32V003_SPI_DIRECTION_1LINE_TX)
#warning "both CH32V003_SPI_DIRECTION_ options were defined!"
#endif

#if ((defined(CH32V003_SPI_CLK_MODE_POL0_PHA0) ? 1 : 0) + \
     (defined(CH32V003_SPI_CLK_MODE_POL0_PHA1) ? 1 : 0) + \
     (defined(CH32V003_SPI_CLK_MODE_POL1_PHA0) ? 1 : 0) + \
     (defined(CH32V003_SPI_CLK_MODE_POL1_PHA1) ? 1 : 0)) > 1
#warning "more than one of the CH32V003_SPI_CLK_MODE_ options were defined!"
#endif
#if ((defined(CH32V003_SPI_CLK_MODE_POL0_PHA0) ? 1 : 0) + \
     (defined(CH32V003_SPI_CLK_MODE_POL0_PHA1) ? 1 : 0) + \
     (defined(CH32V003_SPI_CLK_MODE_POL1_PHA0) ? 1 : 0) + \
     (defined(CH32V003_SPI_CLK_MODE_POL1_PHA1) ? 1 : 0)) == 0
#warning "none of the CH32V003_SPI_CLK_MODE_ options were defined!"
#endif

#if ((defined(CH32V003_SPI_NSS_HARDWARE_PC0) ? 1 : 0) + \
     (defined(CH32V003_SPI_NSS_HARDWARE_PC1) ? 1 : 0) + \
     (defined(CH32V003_SPI_NSS_SOFTWARE_PC3) ? 1 : 0) + \
     (defined(CH32V003_SPI_NSS_SOFTWARE_PC4) ? 1 : 0) + \
     (defined(CH32V003_SPI_NSS_SOFTWARE_ANY_MANUAL) ? 1 : 0)) > 1
#warning "more than one of the CH32V003_SPI_NSS_ options were defined!"
#endif
#if ((defined(CH32V003_SPI_NSS_HARDWARE_PC0) ? 1 : 0) + \
     (defined(CH32V003_SPI_NSS_HARDWARE_PC1) ? 1 : 0) + \
     (defined(CH32V003_SPI_NSS_SOFTWARE_PC3) ? 1 : 0) + \
     (defined(CH32V003_SPI_NSS_SOFTWARE_PC4) ? 1 : 0) + \
     (defined(CH32V003_SPI_NSS_SOFTWARE_ANY_MANUAL) ? 1 : 0)) == 0
#warning "none of the CH32V003_SPI_NSS_ options were defined!"
#endif

// ########  small function definitions, static inline
static inline void SPI_init()
{
    SPI_poweron();

    // reset control register
    SPI1->CTLR1 = 0;

    // set prescaler
    SPI1->CTLR1 |= SPI_CTLR1_BR & (SPI_CLK_PRESCALER << 3);

// set clock polarity and phase
#if defined(CH32V003_SPI_CLK_MODE_POL0_PHA0)
    SPI1->CTLR1 |= (SPI_CPOL_Low | SPI_CPHA_1Edge);
#elif defined(CH32V003_SPI_CLK_MODE_POL0_PHA1)
    SPI1->CTLR1 |= (SPI_CPOL_Low | SPI_CPHA_2Edge);
#elif defined(CH32V003_SPI_CLK_MODE_POL1_PHA0)
    SPI1->CTLR1 |= (SPI_CPOL_High | SPI_CPHA_1Edge);
#elif defined(CH32V003_SPI_CLK_MODE_POL1_PHA1)
    SPI1->CTLR1 |= (SPI_CPOL_High | SPI_CPHA_2Edge);
#endif

// configure NSS pin, master mode
#if defined(CH32V003_SPI_NSS_HARDWARE_PC0)
    // _NSS (negative slave select) on PC0, 10MHz Output, alt func, push-pull1
    SPI1->CTLR1 |= SPI_NSS_Hard; // NSS hardware control mode
    GPIOC->CFGLR &= ~(0xf << (4 * 0));
    GPIOC->CFGLR |= (GPIO_Speed_10MHz | GPIO_CNF_OUT_PP_AF) << (4 * 0);
    AFIO->PCFR1 |= GPIO_Remap_SPI1; // remap NSS (C1) to _NSS (C0)
    SPI1->CTLR2 |= SPI_CTLR2_SSOE;  // pull _NSS high
#elif defined(CH32V003_SPI_NSS_HARDWARE_PC1)
    // NSS (negative slave select) on PC1, 10MHz Output, alt func, push-pull1
    SPI1->CTLR1 |= SPI_NSS_Hard; // NSS hardware control mode
    GPIOC->CFGLR &= ~(0xf << (4 * 1));
    GPIOC->CFGLR |= (GPIO_Speed_10MHz | GPIO_CNF_OUT_PP_AF) << (4 * 1);
    SPI1->CTLR2 |= SPI_CTLR2_SSOE; // pull _NSS high
#elif defined(CH32V003_SPI_NSS_SOFTWARE_PC3)
    SPI1->CTLR1 |= SPI_NSS_Soft; // SSM NSS software control mode
    GPIOC->CFGLR &= ~(0xf << (4 * 3));
    GPIOC->CFGLR |= (GPIO_Speed_10MHz | GPIO_CNF_OUT_PP_AF) << (4 * 3);
#elif defined(CH32V003_SPI_NSS_SOFTWARE_PC4)
    SPI1->CTLR1 |= SPI_NSS_Soft; // SSM NSS software control mode
    GPIOC->CFGLR &= ~(0xf << (4 * 4));
    GPIOC->CFGLR |= (GPIO_Speed_10MHz | GPIO_CNF_OUT_PP_AF) << (4 * 4);
#elif defined(CH32V003_SPI_NSS_SOFTWARE_ANY_MANUAL)
    SPI1->CTLR1 |= SPI_NSS_Soft; // SSM NSS software control mode
#endif

    // SCK on PC5, 10MHz Output, alt func, push-pull
    GPIOC->CFGLR &= ~(0xf << (4 * 5));
    GPIOC->CFGLR |= (GPIO_Speed_50MHz | GPIO_CNF_OUT_PP_AF) << (4 * 5);

    // CH32V003 is master
    SPI1->CTLR1 |= SPI_Mode_Master;

// set data direction and configure data pins
#if defined(CH32V003_SPI_DIRECTION_2LINE_TXRX)
    SPI1->CTLR1 |= SPI_Direction_2Lines_FullDuplex;

    // MOSI on PC6, 10MHz Output, alt func, push-pull
    GPIOC->CFGLR &= ~(0xf << (4 * 6));
    GPIOC->CFGLR |= (GPIO_Speed_50MHz | GPIO_CNF_OUT_PP_AF) << (4 * 6);

    // MISO on PC7, 10MHz input, floating
    GPIOC->CFGLR &= ~(0xf << (4 * 7));
    GPIOC->CFGLR |= GPIO_CNF_IN_FLOATING << (4 * 7);
#elif defined(CH32V003_SPI_DIRECTION_1LINE_TX)
    SPI1->CTLR1 |= SPI_Direction_1Line_Tx;

    // MOSI on PC6, 10MHz Output, alt func, push-pull
    GPIOC->CFGLR &= ~(0xf << (4 * 6));
    GPIOC->CFGLR |= (GPIO_Speed_50MHz | GPIO_CNF_OUT_PP_AF) << (4 * 6);
#endif
}

static inline void SPI_begin_8()
{
    SPI1->CTLR1 &= ~(SPI_CTLR1_DFF); // DFF 16bit data-length enable, writable only when SPE is 0
    SPI1->CTLR1 |= SPI_CTLR1_SPE;
}
static inline void SPI_begin_16()
{
    SPI1->CTLR1 |= SPI_CTLR1_DFF; // DFF 16bit data-length enable, writable only when SPE is 0
    SPI1->CTLR1 |= SPI_CTLR1_SPE;
}
static inline void SPI_end()
{
    SPI1->CTLR1 &= ~(SPI_CTLR1_SPE);
}

#if defined(CH32V003_SPI_NSS_SOFTWARE_PC3)
static inline void SPI_NSS_software_high()
{
    GPIOC->BSHR = (1 << 3);
}
static inline void SPI_NSS_software_low()
{
    GPIOC->BSHR = (1 << (16 + 3));
}
#elif defined(CH32V003_SPI_NSS_SOFTWARE_PC4)
static inline void SPI_NSS_software_high()
{
    GPIOC->BSHR = (1 << 4);
}
static inline void SPI_NSS_software_low()
{
    GPIOC->BSHR = (1 << (16 + 4));
}
#endif

static inline uint8_t SPI_read_8()
{
    return SPI1->DATAR;
}
static inline uint16_t SPI_read_16()
{
    return SPI1->DATAR;
}
static inline void SPI_write_8(uint8_t data)
{
    SPI1->DATAR = data;
}
static inline void SPI_write_16(uint16_t data)
{
    SPI1->DATAR = data;
}
static inline uint8_t SPI_transfer_8(uint8_t data)
{
#if defined(CH32V003_SPI_NSS_SOFTWARE_PC3) || defined(CH32V003_SPI_NSS_SOFTWARE_PC4)
    SPI_NSS_software_high();
#endif
    SPI_write_8(data);
    SPI_wait_TX_complete();
    asm volatile("nop");
    SPI_wait_RX_available();
#if defined(CH32V003_SPI_NSS_SOFTWARE_PC3) || defined(CH32V003_SPI_NSS_SOFTWARE_PC4)
    SPI_NSS_software_low();
#endif
    return SPI_read_8();
}
static inline uint16_t SPI_transfer_16(uint16_t data)
{
#if defined(CH32V003_SPI_NSS_SOFTWARE_PC3) || defined(CH32V003_SPI_NSS_SOFTWARE_PC4)
    SPI_NSS_software_high();
#endif
    SPI_write_16(data);
    SPI_wait_TX_complete();
    asm volatile("nop");
    SPI_wait_RX_available();
#if defined(CH32V003_SPI_NSS_SOFTWARE_PC3) || defined(CH32V003_SPI_NSS_SOFTWARE_PC4)
    SPI_NSS_software_low();
#endif
    return SPI_read_16();
}

static inline void SPI_poweroff()
{
    SPI_end();
    RCC->APB2PCENR &= ~RCC_APB2Periph_SPI1;
}
static inline void SPI_poweron()
{
    RCC->APB2PCENR |= RCC_APB2Periph_GPIOC | RCC_APB2Periph_SPI1;
}

static inline void kill_interrrupts()
{
    EXT1_INTENR_backup = EXTI->INTENR;
    // zero the interrupt enable register to disable all interrupts
    EXTI->INTENR = 0;
}
static inline void restore_interrupts()
{
    EXTI->INTENR = EXT1_INTENR_backup;
}

// ########  small internal function definitions, static inline
static inline void SPI_wait_TX_complete()
{
    while (!(SPI1->STATR & SPI_STATR_TXE)) {}
}
static inline uint8_t SPI_is_RX_empty()
{
    return SPI1->STATR & SPI_STATR_RXNE;
}
static inline void SPI_wait_RX_available()
{
    while (!(SPI1->STATR & SPI_STATR_RXNE)) {}
}
static inline void SPI_wait_not_busy()
{
    while ((SPI1->STATR & SPI_STATR_BSY) != 0) {}
}
static inline void SPI_wait_transmit_finished()
{
    SPI_wait_TX_complete();
    SPI_wait_not_busy();
}

// ######## implementation block
// #define CH32V003_SPI_IMPLEMENTATION //enable so LSP can give you text colors while working on the implementation block, disable for normal use of the library
#if defined(CH32V003_SPI_IMPLEMENTATION)

// no functions here because I think all of the functions are small enough to static inline

#endif // CH32V003_SPI_IMPLEMENTATION
#endif // CH32V003_SPI_H