/* SPDX-License-Identifier: LGPL-2.1 OR MIT */
/*
 * parisc/hppa (32-bit) specific definitions for NOLIBC
 * Copyright (C) 2026 Thomas Weißschuh <linux@weissschuh.net>
 */

#ifndef _NOLIBC_ARCH_PARISC_H
#define _NOLIBC_ARCH_PARISC_H

#if defined(__LP64__)
#error 64-bit not supported
#endif

#include "compiler.h"
#include "crt.h"

/* Syscalls for parisc :
 *   - syscall number is passed in r20
 *   - arguments are in r26 to r21
 *   - the system call is performed by calling "ble 0x100(%sr2, %r0)",
 *     the instruction after that is in the delay slot and executed before
 *     the jump to 0x100 actually happens, use it to load the syscall number
 *   - syscall return comes in r28
 *   - the arguments are cast to long and assigned into the target
 *     registers which are then simply passed as registers to the asm code,
 *     so that we don't have to experience issues with register constraints.
 */

#define _NOLIBC_SYSCALL_CLOBBERLIST \
        "memory", "%r1", "%r2", "%r4", "%r20", "%r29", "%r31"

#define __nolibc_syscall0(num)                                                \
({                                                                            \
        register long _ret __asm__ ("r28");                                   \
                                                                              \
        __asm__ volatile (                                                    \
                "ble 0x100(%%sr2, %%r0)\n\t"                                  \
                "copy %1, %%r20\n\t"                                          \
                : "=r"(_ret)                                                  \
                : "r"(num)                                                    \
                : _NOLIBC_SYSCALL_CLOBBERLIST,                                \
                  "%r21", "%r22", "%r23", "%r24", "%r25", "%r26"              \
        );                                                                    \
        _ret;                                                                 \
})

#define __nolibc_syscall1(num, arg1)                                          \
({                                                                            \
        register long _ret __asm__ ("r28");                                   \
        register long _arg1 __asm__ ("r26") = (long)(arg1);                   \
                                                                              \
        __asm__ volatile (                                                    \
                "ble 0x100(%%sr2, %%r0)\n\t"                                  \
                "copy %2, %%r20\n\t"                                          \
                : "=r"(_ret),                                                 \
                  "+r"(_arg1)                                                 \
                : "r"(num)                                                    \
                : _NOLIBC_SYSCALL_CLOBBERLIST,                                \
                  "%r21", "%r22", "%r23", "%r24", "%r25"                      \
        );                                                                    \
        _ret;                                                                 \
})

#define __nolibc_syscall2(num, arg1, arg2)                                    \
({                                                                            \
        register long _ret __asm__ ("r28");                                   \
        register long _arg1 __asm__ ("r26") = (long)(arg1);                   \
        register long _arg2 __asm__ ("r25") = (long)(arg2);                   \
                                                                              \
        __asm__ volatile (                                                    \
                "ble 0x100(%%sr2, %%r0)\n\t"                                  \
                "copy %3, %%r20\n\t"                                          \
                : "=r"(_ret),                                                 \
                  "+r"(_arg1), "+r"(_arg2)                                    \
                : "r"(num)                                                    \
                : _NOLIBC_SYSCALL_CLOBBERLIST,                                \
                  "%r21", "%r22", "%r23", "%r24"                              \
        );                                                                    \
        _ret;                                                                 \
})

#define __nolibc_syscall3(num, arg1, arg2, arg3)                              \
({                                                                            \
        register long _ret __asm__ ("r28");                                   \
        register long _arg1 __asm__ ("r26") = (long)(arg1);                   \
        register long _arg2 __asm__ ("r25") = (long)(arg2);                   \
        register long _arg3 __asm__ ("r24") = (long)(arg3);                   \
                                                                              \
        __asm__ volatile (                                                    \
                "ble 0x100(%%sr2, %%r0)\n\t"                                  \
                "copy %4, %%r20\n\t"                                          \
                : "=r"(_ret),                                                 \
                  "+r"(_arg1), "+r"(_arg2), "+r"(_arg3)                       \
                : "r"(num)                                                    \
                : _NOLIBC_SYSCALL_CLOBBERLIST,                                \
                  "%r21", "%r22", "%r23"                                      \
        );                                                                    \
        _ret;                                                                 \
})

#define __nolibc_syscall4(num, arg1, arg2, arg3, arg4)                        \
({                                                                            \
        register long _ret __asm__ ("r28");                                   \
        register long _arg1 __asm__ ("r26") = (long)(arg1);                   \
        register long _arg2 __asm__ ("r25") = (long)(arg2);                   \
        register long _arg3 __asm__ ("r24") = (long)(arg3);                   \
        register long _arg4 __asm__ ("r23") = (long)(arg4);                   \
                                                                              \
        __asm__ volatile (                                                    \
                "ble 0x100(%%sr2, %%r0)\n\t"                                  \
                "copy %5, %%r20\n\t"                                          \
                : "=r"(_ret),                                                 \
                  "+r"(_arg1), "+r"(_arg2), "+r"(_arg3), "+r"(_arg4)          \
                : "r"(num)                                                    \
                : _NOLIBC_SYSCALL_CLOBBERLIST,                                \
                  "%r21", "%r22"                                              \
        );                                                                    \
        _ret;                                                                 \
})

#define __nolibc_syscall5(num, arg1, arg2, arg3, arg4, arg5)                  \
({                                                                            \
        register long _ret __asm__ ("r28");                                   \
        register long _arg1 __asm__ ("r26") = (long)(arg1);                   \
        register long _arg2 __asm__ ("r25") = (long)(arg2);                   \
        register long _arg3 __asm__ ("r24") = (long)(arg3);                   \
        register long _arg4 __asm__ ("r23") = (long)(arg4);                   \
        register long _arg5 __asm__ ("r22") = (long)(arg5);                   \
                                                                              \
        __asm__ volatile (                                                    \
                "ble 0x100(%%sr2, %%r0)\n\t"                                  \
                "copy %6, %%r20\n\t"                                          \
                : "=r"(_ret),                                                 \
                  "+r"(_arg1), "+r"(_arg2), "+r"(_arg3), "+r"(_arg4),         \
                  "+r"(_arg5)                                                 \
                : "r"(num)                                                    \
                : _NOLIBC_SYSCALL_CLOBBERLIST,                                \
                  "%r21"                                                      \
        );                                                                    \
        _ret;                                                                 \
})

#define __nolibc_syscall6(num, arg1, arg2, arg3, arg4, arg5, arg6)            \
({                                                                            \
        register long _ret __asm__ ("r28");                                   \
        register long _arg1 __asm__ ("r26") = (long)(arg1);                   \
        register long _arg2 __asm__ ("r25") = (long)(arg2);                   \
        register long _arg3 __asm__ ("r24") = (long)(arg3);                   \
        register long _arg4 __asm__ ("r23") = (long)(arg4);                   \
        register long _arg5 __asm__ ("r22") = (long)(arg5);                   \
        register long _arg6 __asm__ ("r21") = (long)(arg6);                   \
                                                                              \
        __asm__ volatile (                                                    \
                "ble 0x100(%%sr2, %%r0)\n\t"                                  \
                "copy %7, %%r20\n\t"                                          \
                : "=r"(_ret),                                                 \
                  "+r"(_arg1), "+r"(_arg2), "+r"(_arg3), "+r"(_arg4),         \
                  "+r"(_arg5), "+r"(_arg6)                                    \
                : "r"(num)                                                    \
                : _NOLIBC_SYSCALL_CLOBBERLIST                                 \
        );                                                                    \
        _ret;                                                                 \
})

#ifndef NOLIBC_NO_RUNTIME
/* startup code */
void __attribute__((weak, noreturn)) __nolibc_entrypoint __nolibc_no_stack_protector _start(void)
{
        __asm__ volatile (
                ".import $global$\n"           /* Set up the dp register */
                "ldil L%$global$, %dp\n"
                "ldo R%$global$(%r27), %dp\n"

                "b _start_c\n"                 /* Call _start_c, the load below is executed first */

                "ldo -4(%r24), %r26\n"         /* The sp register is special on parisc.
                                                * r24 points to argv. Subtract 4 to get &argc.
                                                * Pass that as first argument to _start_c.
                                                */
        );
        __nolibc_entrypoint_epilogue();
}
#endif /* NOLIBC_NO_RUNTIME */

#endif /* _NOLIBC_ARCH_PARISC_H */