From d106235f5eebe280f4f820fc29bb5d8708e2f54d Mon Sep 17 00:00:00 2001
From: Matt Turner <mattst88@gmail.com>
Date: Mon, 23 May 2016 18:10:11 -0700
Subject: Initial import

---
 clear_page.c | 88 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 88 insertions(+)
 create mode 100644 clear_page.c

(limited to 'clear_page.c')

diff --git a/clear_page.c b/clear_page.c
new file mode 100644
index 0000000..6940328
--- /dev/null
+++ b/clear_page.c
@@ -0,0 +1,88 @@
+/* vim: set expandtab tabstop=4 softtabstop=4 shiftwidth=4: */
+
+#define PAGE_SIZE 8192
+
+#define wh64(p) asm ("wh64 (%0)" : : "r"(p) : "memory")
+#define ecb(p) asm("ecb (%0)" : : "r"(p) : "memory")
+#define prefetch(p) asm("ldl $31, 0(%0)" : : "r"(p))
+#define prefetch_en(p) asm("ldq $31, 0(%0)" : : "r"(p))
+#define prefetch_m(p) asm("lds $f31, 0(%0)" : : "r"(p))
+#define prefetch_men(p) asm("ldt $f31, 0(%0)" : : "r"(p))
+#define nop asm("nop")
+
+#define PREFETCH_LINES 2
+
+//#define UNROLL_EVERYTHING
+
+#define ZERO(p) do { \
+	prefetch_m(p + PREFETCH_LINES * 8); \
+	(p)[0] = 0; nop; (p)[1] = 0; nop; (p)[2] = 0; nop; (p)[3] = 0; nop; \
+	(p)[4] = 0; nop; (p)[5] = 0; nop; (p)[6] = 0; nop; (p)[7] = 0; nop; \
+	p += 8; \
+} while (0)
+
+#define ZERO_PAGE(p) do { \
+	ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); \
+	ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); \
+	ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); \
+	ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); \
+	ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); \
+	ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); \
+	ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); \
+	ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); \
+	ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); \
+	ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); \
+	ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); \
+	ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); \
+	ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); \
+	ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); \
+	ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); \
+	ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); ZERO(p); \
+} while (0)
+
+void
+clear_page(void *page)
+{
+    int chunks = PAGE_SIZE / 64;
+    int chunks_prefetch = chunks - PREFETCH_LINES;
+    int chunks_no_prefetch = PREFETCH_LINES;
+
+    long *p = page;
+#ifdef UNROLL_EVERYTHING
+    long *end = page + PAGE_SIZE;
+    ZERO_PAGE(p);
+#else
+    while (chunks_prefetch > 0) {
+        prefetch_m(p + PREFETCH_LINES * 8);
+        p[0] = 0; nop;
+        p[1] = 0; nop;
+        p[2] = 0; nop;
+        p[3] = 0; nop;
+        p[4] = 0; nop;
+        p[5] = 0; nop;
+        p[6] = 0; nop;
+        p[7] = 0; nop;
+
+        nop; nop; nop; nop;
+
+        chunks_prefetch--;
+        p += 8;
+    }
+
+    while (chunks_no_prefetch > 0) {
+        p[0] = 0; nop;
+        p[1] = 0; nop;
+        p[2] = 0; nop;
+        p[3] = 0; nop;
+        p[4] = 0; nop;
+        p[5] = 0; nop;
+        p[6] = 0; nop;
+        p[7] = 0; nop;
+
+        nop; nop; nop; nop;
+
+        chunks_no_prefetch--;
+        p += 8;
+    }
+#endif
+}
-- 
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