#ifndef VLIBC_SETJMP_H
#define VLIBC_SETJMP_H

/*
 * vlibc — <setjmp.h>.
 *
 * Non-local jumps. setjmp(env) saves the calling environment and returns 0;
 * longjmp(env, val) makes that setjmp return val, with 0 coerced to 1 so the
 * two returns are distinguishable. sigsetjmp/siglongjmp additionally save and
 * restore the signal mask when the buffer's saved-mask flag is set.
 *
 * jmp_buf is an array type (C23 7.13.1 requires it); both types below are
 * arrays of unsigned long. The word layout is ABI: the x86_64 assembly in
 * src/setjmp/x86_64/{setjmp,longjmp,sigsetjmp,siglongjmp}.s reads and writes
 * exactly these slots. This comment is the single authoritative map — keep it
 * and those files in sync:
 *
 *   [0] rbx             callee-saved general registers (System V AMD64 ABI)
 *   [1] rbp
 *   [2] r12
 *   [3] r13
 *   [4] r14
 *   [5] r15
 *   [6] rsp             the caller's stack pointer (just past the return address)
 *   [7] rip             the return address, where longjmp resumes execution
 *   [8] mxcsr           SSE control/status register (stmxcsr/ldmxcsr)
 *   [9] x87 cw          x87 control word (fnstcw/fldcw)
 *
 * sigjmp_buf extends the base layout with two more words:
 *
 *   [10] saved-mask flag (1 when the signal mask was saved)
 *   [11] signal mask     (the x86_64 Linux sigset_t: a single 64-bit word)
 *
 * Because the base layout occupies words 0..9 of both types, the plain
 * setjmp/longjmp assembly works verbatim on sigjmp_buf storage as well.
 */

#include <vlibc/features.h>

#ifdef __cplusplus
extern "C" {
#endif

/* Word counts and per-slot indices (see the authoritative map above). */
#define VLIBC_JMP_BUF_WORDS 10
#define VLIBC_JMP_RBX 0
#define VLIBC_JMP_RBP 1
#define VLIBC_JMP_R12 2
#define VLIBC_JMP_R13 3
#define VLIBC_JMP_R14 4
#define VLIBC_JMP_R15 5
#define VLIBC_JMP_RSP 6
#define VLIBC_JMP_RIP 7
#define VLIBC_JMP_MXCSR 8
#define VLIBC_JMP_X87CW 9

#define VLIBC_SIGJMP_BUF_WORDS 12
#define VLIBC_SIGJMP_FLAG 10
#define VLIBC_SIGJMP_MASK 11

typedef unsigned long jmp_buf[VLIBC_JMP_BUF_WORDS];
typedef unsigned long sigjmp_buf[VLIBC_SIGJMP_BUF_WORDS];

/*
 * Save the calling environment and return 0; after longjmp(env, val) the
 * matching setjmp invocation returns val. A macro (C23 7.13.1: usable without
 * a prototype in scope); it expands to _setjmp(env).
 */
#define setjmp(env) _setjmp(env)

/*
 * Like setjmp, plus the current signal mask is saved into env when savemask is
 * nonzero (siglongjmp then restores it). Macro expanding to
 * __sigsetjmp(env, savemask).
 */
#define sigsetjmp(env, savemask) __sigsetjmp(env, savemask)

/*
 * The save behind the setjmp macro; identical semantics (POSIX _setjmp).
 */
int
_setjmp(jmp_buf env); // NOLINT(bugprone-reserved-identifier)

/*
 * Restore the environment saved by _setjmp/setjmp and make it return val, with
 * 0 coerced to 1. Does not return.
 */
__attribute__((noreturn)) void
_longjmp(jmp_buf env, int val); // NOLINT(bugprone-reserved-identifier)

/*
 * ISO C longjmp: same as _longjmp.
 */
__attribute__((noreturn)) void
longjmp(jmp_buf env, int val);

/*
 * The save behind the sigsetjmp macro. Implementation-reserved name, so the
 * public API keeps only the macro; declared because the macro expansion must
 * have a prototype in scope (C23 removed implicit declarations).
 */
int
__sigsetjmp(sigjmp_buf env, int savemask); // NOLINT(bugprone-reserved-identifier)

/*
 * Restore the environment saved by sigsetjmp and make it return val, with 0
 * coerced to 1; when the buffer's saved-mask flag is set, the signal mask is
 * restored first. Does not return.
 */
__attribute__((noreturn)) void
siglongjmp(sigjmp_buf env, int val);

#ifdef __cplusplus
}
#endif

#endif /* VLIBC_SETJMP_H */