#ifndef __HW_COMMON_H
#define __HW_COMMON_H

#include <stdint.h>

/* To overwrite CSR accessors, define extern, non-inlined versions
 * of csr_read[bwl]() and csr_write[bwl](), and define
 * CSR_ACCESSORS_DEFINED.
 */

#ifndef CSR_ACCESSORS_DEFINED
#define CSR_ACCESSORS_DEFINED

#ifdef __ASSEMBLER__
#define MMPTR(x) x
#else /* ! __ASSEMBLER__ */

/* CSRs are stored in subregister slices of CONFIG_CSR_DATA_WIDTH (native
 * endianness), with the least significant slice at the lowest aligned
 * (base) address. */

#include <generated/soc.h>
#if !defined(CONFIG_CSR_ALIGNMENT) || !defined(CONFIG_CSR_DATA_WIDTH)
#error csr alignment and data-width MUST be set before including this file!
#endif

#if CONFIG_CSR_DATA_WIDTH > CONFIG_CSR_ALIGNMENT
#error invalid CONFIG_CSR_DATA_WIDTH (must not exceed CONFIG_CSR_ALIGNMENT)!
#endif

#define CSR_ADDR_INC sizeof(unsigned long) // a.k.a. CONFIG_CSR_ALIGNMENT/8
/* FIXME: preprocessor can't evaluate 'sizeof()' operator !!!
  #if CSR_ADDR_INC != CONFIG_CSR_ALIGNMENT/8
  #error invalid CONFIG_CSR_ALIGNMENT (must match native CPU word size)!
  #endif
*/

/* CSR subregisters are embedded inside native CPU word aligned locations: */
#define MMPTR(a) (*((volatile unsigned long *)(a)))

/* Number of subregs required for various int types, given subreg. width:
 *  +-----+------------+
 *  | csr | sizeof(v)  |
 *  | _dw | 1  2  4  8 |
 *  |     |------------|
 *  |  1  | 1  2  4  8 |
 *  |  2  | 1  1  2  4 |
 *  |  4  | 1  1  1  2 |
 *  |  8  | 1  1  1  1 |
 *  +-----+------------+ */
#define _CSR_N_SUBS(v) ((sizeof(v) - 1) / (CONFIG_CSR_DATA_WIDTH / 8) + 1)

#define _CSR_REG_WR(v, a) \
{ \
    int n_subs = _CSR_N_SUBS(v); \
    for (int i = 0; i < n_subs; i++) \
        MMPTR((a) + CSR_ADDR_INC * i) = \
            v >> (CONFIG_CSR_DATA_WIDTH * (n_subs - 1 - i)); \
}

#define _CSR_REG_RD(r, a) \
{ \
    int n_subs = _CSR_N_SUBS(r); \
    r = 0; \
    for (int i = 0; i < n_subs; i++) \
        r |= MMPTR((a) + CSR_ADDR_INC * i) << \
            (CONFIG_CSR_DATA_WIDTH * (n_subs - 1 - i)); \
}

static inline void csr_wr_uint8(uint8_t v, unsigned long a)
{
    _CSR_REG_WR(v, a);
}

static inline void csr_wr_uint16(uint16_t v, unsigned long a)
{
    _CSR_REG_WR(v, a);
}

static inline void csr_wr_uint32(uint32_t v, unsigned long a)
{
    _CSR_REG_WR(v, a);
}

static inline void csr_wr_uint64(uint64_t v, unsigned long a)
{
    _CSR_REG_WR(v, a);
}

static inline uint8_t csr_rd_uint8(unsigned long a)
{
    uint8_t r;
    _CSR_REG_RD(r, a);
    return r;
}

static inline uint16_t csr_rd_uint16(unsigned long a)
{
    uint16_t r;
    _CSR_REG_RD(r, a);
    return r;
}

static inline uint32_t csr_rd_uint32(unsigned long a)
{
    uint32_t r;
    _CSR_REG_RD(r, a);
    return r;
}

static inline uint64_t csr_rd_uint64(unsigned long a)
{
    uint64_t r;
    _CSR_REG_RD(r, a);
    return r;
}

#endif /* ! __ASSEMBLER__ */

#endif /* ! CSR_ACCESSORS_DEFINED */

#endif /* __HW_COMMON_H */