ref: 28c7a3df5e83d66ff94937da059dcb90800d4884
parent: 6804d96d7d8a2dd12e28ea08819fc5f2c59cf724
author: Ori Bernstein <[email protected]>
date: Mon Dec 22 13:50:36 EST 2014
Now util+plan9.s isn't a stub.
--- a/libstd/util+plan9.s
+++ b/libstd/util+plan9.s
@@ -1,0 +1,67 @@
+/*
+ * Allocates a C string on the stack, for
+ * use within system calls, which is the only
+ * place the Myrddin stack should need nul-terminated
+ * strings.
+ *
+ * This is in assembly, because for efficiency we
+ * allocate the C strings on the stack, and don't adjust
+ * SP when returning.
+ */
+TEXT sys$cstring+0(SB),$0
+ /* save registers */
+ PUSHQ BP
+ MOVQ SP,BP
+ PUSHQ R15
+ PUSHQ SI
+ PUSHQ DI
+ PUSHQ CX
+
+ MOVQ 8(BP),R15 /* ret addr */
+ MOVQ 16(BP),SI /* src */
+ MOVQ 24(BP),CX /* len */
+
+ SUBQ CX,SP /* get stack */
+ SUBQ $1,SP /* +1 for nul */
+ MOVQ SP,DI /* dest */
+ MOVQ SP,AX /* ret val */
+ SUBQ $16,SP /* "unpop" the args */
+ ANDQ $(~15),SP /* align */
+
+ CLD
+ REP; MOVSB
+ MOVB $0,(DI) /* terminate */
+
+ PUSHQ R15 /* ret addr */
+
+ /* Restore registers */
+ MOVQ -32(BP),CX
+ MOVQ -24(BP),DI
+ MOVQ -16(BP),SI
+ MOVQ -8(BP),R15
+ MOVQ (BP),BP
+ RET
+
+TEXT sys$alloca+0(SB),$0
+ /* save registers */
+ PUSHQ BP
+ MOVQ SP,BP
+ PUSHQ R15
+ PUSHQ BX
+
+ MOVQ 8(BP),R15 /* ret addr */
+ MOVQ 16(BP),BX /* len */
+
+ /* get stack space */
+ SUBQ BX,SP /* get stack space */
+ MOVQ SP,AX /* top of stack (return value) */
+ SUBQ $16,SP /* "unpop" the args for return */
+ ANDQ $(~15),SP /* align */
+
+ PUSHQ R15 /* ret addr */
+
+ /* restore registers */
+ MOVQ -16(BP),BX
+ MOVQ -8(BP),R15
+ MOVQ (BP),BP
+ RET