From 920328bc9eb44906cb3c7eedd518c1672833b16c Mon Sep 17 00:00:00 2001
From: Tau <tau@nowhere>
Date: Wed, 7 Nov 2018 20:03:25 -0500
Subject: [PATCH] nu/sram.c: Add emulated SRAM device

---
 nu/guid.c      |   1 +
 nu/meson.build |   2 +
 nu/sram.c      | 118 +++++++++++++++++++++++++++++++++++++++++++++++++
 nu/sram.h      |  12 +++++
 4 files changed, 133 insertions(+)
 create mode 100644 nu/sram.c
 create mode 100644 nu/sram.h

diff --git a/nu/guid.c b/nu/guid.c
index f2f706f..3ea1064 100644
--- a/nu/guid.c
+++ b/nu/guid.c
@@ -2,3 +2,4 @@
 #include <initguid.h>
 
 #include "nu/eeprom.h"
+#include "nu/sram.h"
diff --git a/nu/meson.build b/nu/meson.build
index f827bb9..d4aaeaf 100644
--- a/nu/meson.build
+++ b/nu/meson.build
@@ -13,5 +13,7 @@ nu_lib = static_library(
         'guid.c',
         'nvram.c',
         'nvram.h',
+        'sram.c',
+        'sram.h',
     ],
 )
diff --git a/nu/sram.c b/nu/sram.c
new file mode 100644
index 0000000..08083d6
--- /dev/null
+++ b/nu/sram.c
@@ -0,0 +1,118 @@
+#include <windows.h>
+
+#include "hook/iohook.h"
+
+#include "nu/sram.h"
+#include "nu/nvram.h"
+
+#include "util/dprintf.h"
+#include "util/setupapi.h"
+
+static HRESULT sram_handle_irp(struct irp *irp);
+static HRESULT sram_handle_open(struct irp *irp);
+static HRESULT sram_handle_close(struct irp *irp);
+static HRESULT sram_handle_ioctl(struct irp *irp);
+
+static HRESULT sram_ioctl_get_geometry(struct irp *irp);
+
+static HANDLE sram_file;
+
+HRESULT sram_hook_init(void)
+{
+    HRESULT hr;
+
+    hr = nvram_open_file(&sram_file, L"DEVICE\\sram.bin", 0x80000);
+
+    if (FAILED(hr)) {
+        return hr;
+    }
+
+    hr = iohook_push_handler(sram_handle_irp);
+
+    if (FAILED(hr)) {
+        return hr;
+    }
+
+    hr = setupapi_add_phantom_dev(&sram_guid, L"$sram");
+
+    if (FAILED(hr)) {
+        return hr;
+    }
+
+    return S_OK;
+}
+
+static HRESULT sram_handle_irp(struct irp *irp)
+{
+    assert(irp != NULL);
+
+    if (irp->op != IRP_OP_OPEN && irp->fd != sram_file) {
+        return iohook_invoke_next(irp);
+    }
+
+    switch (irp->op) {
+    case IRP_OP_OPEN:   return sram_handle_open(irp);
+    case IRP_OP_CLOSE:  return sram_handle_close(irp);
+    case IRP_OP_IOCTL:  return sram_handle_ioctl(irp);
+    default:            return iohook_invoke_next(irp);
+    }
+}
+
+static HRESULT sram_handle_open(struct irp *irp)
+{
+    if (wcscmp(irp->open_filename, L"$sram") != 0) {
+        return iohook_invoke_next(irp);
+    }
+
+    dprintf("SRAM: Open device\n");
+    irp->fd = sram_file;
+
+    return S_OK;
+}
+
+static HRESULT sram_handle_close(struct irp *irp)
+{
+    dprintf("SRAM: Close device\n");
+
+    return S_OK;
+}
+
+static HRESULT sram_handle_ioctl(struct irp *irp)
+{
+    switch (irp->ioctl) {
+    case IOCTL_DISK_GET_DRIVE_GEOMETRY:
+        return sram_ioctl_get_geometry(irp);
+
+    default:
+        dprintf("SRAM: Unknown ioctl %x, write %i read %i\n",
+                irp->ioctl,
+                irp->write.nbytes,
+                irp->read.nbytes);
+
+        return HRESULT_FROM_WIN32(ERROR_INVALID_FUNCTION);
+    }
+}
+
+static HRESULT sram_ioctl_get_geometry(struct irp *irp)
+{
+    DISK_GEOMETRY *out;
+
+    if (irp->read.nbytes < sizeof(*out)) {
+        dprintf("SRAM: Invalid ioctl response buffer size\n");
+
+        return HRESULT_FROM_WIN32(ERROR_INSUFFICIENT_BUFFER);
+    }
+
+    dprintf("SRAM: Get geometry\n");
+
+    out = (DISK_GEOMETRY *) irp->read.bytes;
+    out->Cylinders.QuadPart = 0x20000;
+    out->MediaType = 0;
+    out->TracksPerCylinder = 1;
+    out->SectorsPerTrack = 1;
+    out->BytesPerSector = 4;
+
+    irp->read.pos = sizeof(*out);
+
+    return S_OK;
+}
diff --git a/nu/sram.h b/nu/sram.h
new file mode 100644
index 0000000..f2c4c3b
--- /dev/null
+++ b/nu/sram.h
@@ -0,0 +1,12 @@
+#pragma once
+
+#include <windows.h>
+
+DEFINE_GUID(
+        sram_guid,
+        0x741B5FCA,
+        0x4635,
+        0x4443,
+        0xA7, 0xA0, 0x57, 0xCA, 0x7B, 0x50, 0x6A, 0x49);
+
+HRESULT sram_hook_init(void);