user/libc: setjmp

1 files changed, 39 insertions, 0 deletions

diff --git a/src/user/lib/setjmp.s b/src/user/lib/setjmp.s
new file mode 100644
index 0000000..29292da
--- /dev/null
+++ b/src/user/lib/setjmp.s
@@ -0,0 +1,39 @@
+.section .text
+.global setjmp
+.type setjmp, @function
+// int setjmp(jmp_buf env);
+setjmp:
+	mov  %rbx,  0(%rdi)
+	mov  %rbp, 16(%rdi)
+	mov  %r12, 24(%rdi)
+	mov  %r13, 32(%rdi)
+	mov  %r14, 40(%rdi)
+	mov  %r15, 48(%rdi)
+	/* save registers as if after a ret */
+	lea 8(%rsp), %rax
+	mov %rax, 8(%rdi)
+	mov (%rsp), %rax
+	mov %rax, 56(%rdi)
+	xor %rax, %rax
+
+	mov   8(%rdi), %rsp
+	jmp *56(%rdi)
+
+	ret
+
+
+.global longjmp
+.type longjmp, @function
+// _Noreturn void longjmp(jmp_buf env, int val);
+longjmp:
+	mov %rsi, %rax
+	cmp $1, %rax /* carry set as for %rax - 1 - so, 1 only if %rax == 0 */
+	adc $0, %rax
+1:	mov   0(%rdi), %rbx
+	mov   8(%rdi), %rsp
+	mov  16(%rdi), %rbp
+	mov  24(%rdi), %r12
+	mov  32(%rdi), %r13
+	mov  40(%rdi), %r14
+	mov  48(%rdi), %r15
+	jmp *56(%rdi)