go*: one go module for the repo, no more nested

Signed-off-by: Vincent Batts <vbatts@hashbangbash.com>

vendor/github.com/pjbgf/sha1cd/sha1cdblock_amd64.go

@@ -0,0 +1,50 @@
+//go:build !noasm && gc && amd64
+// +build !noasm,gc,amd64
+
+package sha1cd
+
+import (
+	"math"
+	"unsafe"
+
+	shared "github.com/pjbgf/sha1cd/internal"
+)
+
+type sliceHeader struct {
+	base uintptr
+	len  int
+	cap  int
+}
+
+// blockAMD64 hashes the message p into the current state in dig.
+// Both m1 and cs are used to store intermediate results which are used by the collision detection logic.
+//
+//go:noescape
+func blockAMD64(dig *digest, p sliceHeader, m1 []uint32, cs [][5]uint32)
+
+func block(dig *digest, p []byte) {
+	m1 := [shared.Rounds]uint32{}
+	cs := [shared.PreStepState][shared.WordBuffers]uint32{}
+
+	for len(p) >= shared.Chunk {
+		// Only send a block to be processed, as the collission detection
+		// works on a block by block basis.
+		ips := sliceHeader{
+			base: uintptr(unsafe.Pointer(&p[0])),
+			len:  int(math.Min(float64(len(p)), float64(shared.Chunk))),
+			cap:  shared.Chunk,
+		}
+
+		blockAMD64(dig, ips, m1[:], cs[:])
+
+		col := checkCollision(m1, cs, dig.h)
+		if col {
+			dig.col = true
+
+			blockAMD64(dig, ips, m1[:], cs[:])
+			blockAMD64(dig, ips, m1[:], cs[:])
+		}
+
+		p = p[shared.Chunk:]
+	}
+}