am7xxx: make the supported_device array const
[libam7xxx.git] / src / am7xxx.c
index ee9af55..a5e53de 100644 (file)
@@ -4,7 +4,7 @@
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
  *
  * This program is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 3 of the License, or
+ * the Free Software Foundation, either version 2 of the License, or
  * (at your option) any later version.
  *
  * This program is distributed in the hope that it will be useful,
  * (at your option) any later version.
  *
  * This program is distributed in the hope that it will be useful,
  */
 
 #include <stdio.h>
  */
 
 #include <stdio.h>
-#include <endian.h>
+#include <stdlib.h>
+#include <string.h>
+#include <stdarg.h>
 #include <errno.h>
 #include <errno.h>
+#include <libusb.h>
+#include <math.h>
 
 #include "am7xxx.h"
 
 #include "am7xxx.h"
+#include "serialize.h"
 
 
-#define AM7XXX_VENDOR_ID  0x1de1
-#define AM7XXX_PRODUCT_ID 0xc101
-
-#if 1
-static uint8_t reference_image_header[] = {
-       0x02, 0x00, 0x00, 0x00,
-       0x00,
-       0x10,
-       0x3e,
-       0x10,
-       0x01, 0x00, 0x00, 0x00,
-       0x20, 0x03, 0x00, 0x00,
-       0xe0, 0x01, 0x00, 0x00,
-       0x53, 0xE8, 0x00, 0x00
-};
+#define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
+
+/* If we're not using GNU C, elide __attribute__
+ * taken from: http://unixwiz.net/techtips/gnu-c-attributes.html)
+ */
+#ifndef __GNUC__
+#  define  __attribute__(x)  /*NOTHING*/
+#endif
+
+/* Control shared library symbols visibility */
+#if defined _WIN32 || defined __CYGWIN__
+       #define AM7XXX_PUBLIC __declspec(dllexport)
+       #define AM7XXX_LOCAL
+#else
+       #if __GNUC__ >= 4
+               #define AM7XXX_PUBLIC __attribute__ ((visibility ("default")))
+               #define AM7XXX_LOCAL  __attribute__ ((visibility ("hidden")))
+       #else
+               #define AM7XXX_PUBLIC
+               #define AM7XXX_LOCAL
+       #endif
 #endif
 
 #endif
 
-static void dump_image_header(struct am7xxx_image_header *i)
+static void log_message(am7xxx_context *ctx,
+                       int level,
+                       const char *function,
+                       int line,
+                       const char *fmt,
+                       ...) __attribute__ ((format (printf, 5, 6)));
+
+#define fatal(...)        log_message(NULL, AM7XXX_LOG_FATAL,   __func__, __LINE__, __VA_ARGS__)
+#define error(ctx, ...)   log_message(ctx,  AM7XXX_LOG_ERROR,   __func__, __LINE__, __VA_ARGS__)
+#define warning(ctx, ...) log_message(ctx,  AM7XXX_LOG_WARNING, __func__, 0,        __VA_ARGS__)
+#define info(ctx, ...)    log_message(ctx,  AM7XXX_LOG_INFO,    __func__, 0,        __VA_ARGS__)
+#define debug(ctx, ...)   log_message(ctx,  AM7XXX_LOG_DEBUG,   __func__, 0,        __VA_ARGS__)
+#define trace(ctx, ...)   log_message(ctx,  AM7XXX_LOG_TRACE,   NULL,     0,        __VA_ARGS__)
+
+struct am7xxx_usb_device_descriptor {
+       const char *name;
+       uint16_t vendor_id;
+       uint16_t product_id;
+       uint8_t configuration;    /* The bConfigurationValue of the device */
+       uint8_t interface_number; /* The bInterfaceNumber of the device */
+};
+
+static const struct am7xxx_usb_device_descriptor supported_devices[] = {
+       {
+               .name       = "Acer C110",
+               .vendor_id  = 0x1de1,
+               .product_id = 0xc101,
+               .configuration    = 2,
+               .interface_number = 0,
+       },
+       {
+               .name       = "Acer C112",
+               .vendor_id  = 0x1de1,
+               .product_id = 0x5501,
+               .configuration    = 2,
+               .interface_number = 0,
+       },
+       {
+               .name       ="Aiptek PocketCinema T25",
+               .vendor_id  = 0x08ca,
+               .product_id = 0x2144,
+               .configuration    = 2,
+               .interface_number = 0,
+       },
+       {
+               .name       = "Philips/Sagemcom PicoPix 1020",
+               .vendor_id  = 0x21e7,
+               .product_id = 0x000e,
+               .configuration    = 2,
+               .interface_number = 0,
+       },
+       {
+               .name       = "Philips/Sagemcom PicoPix 2055",
+               .vendor_id  = 0x21e7,
+               .product_id = 0x0016,
+               .configuration    = 2,
+               .interface_number = 0,
+       },
+};
+
+/* The header size on the wire is known to be always 24 bytes, regardless of
+ * the memory configuration enforced by different architectures or compilers
+ * for struct am7xxx_header
+ */
+#define AM7XXX_HEADER_WIRE_SIZE 24
+
+struct _am7xxx_device {
+       libusb_device_handle *usb_device;
+       uint8_t buffer[AM7XXX_HEADER_WIRE_SIZE];
+       am7xxx_device_info *device_info;
+       am7xxx_context *ctx;
+       const struct am7xxx_usb_device_descriptor *desc;
+       am7xxx_device *next;
+};
+
+struct _am7xxx_context {
+       libusb_context *usb_context;
+       int log_level;
+       am7xxx_device *devices_list;
+};
+
+typedef enum {
+       AM7XXX_PACKET_TYPE_DEVINFO = 0x01,
+       AM7XXX_PACKET_TYPE_IMAGE   = 0x02,
+       AM7XXX_PACKET_TYPE_POWER   = 0x04,
+       AM7XXX_PACKET_TYPE_ZOOM    = 0x05,
+} am7xxx_packet_type;
+
+struct am7xxx_generic_header {
+       uint32_t field0;
+       uint32_t field1;
+       uint32_t field2;
+       uint32_t field3;
+};
+
+struct am7xxx_devinfo_header {
+       uint32_t native_width;
+       uint32_t native_height;
+       uint32_t unknown0;
+       uint32_t unknown1;
+};
+
+struct am7xxx_image_header {
+       uint32_t format;
+       uint32_t width;
+       uint32_t height;
+       uint32_t image_size;
+};
+
+struct am7xxx_power_header {
+       uint32_t bit2;
+       uint32_t bit1;
+       uint32_t bit0;
+};
+
+struct am7xxx_zoom_header {
+       uint32_t bit1;
+       uint32_t bit0;
+};
+
+/*
+ * Examples of packet headers:
+ *
+ * Image header:
+ * 02 00 00 00 00 10 3e 10 01 00 00 00 20 03 00 00 e0 01 00 00 53 E8 00 00
+ *
+ * Power header:
+ * 04 00 00 00 00 0c ff ff 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
+ */
+
+/* Direction of the communication from the host point of view */
+#define AM7XXX_DIRECTION_OUT 0 /* host -> device */
+#define AM7XXX_DIRECTION_IN  1 /* host <- device */
+
+struct am7xxx_header {
+       uint32_t packet_type;
+       uint8_t direction;
+       uint8_t header_data_len;
+       uint8_t unknown2;
+       uint8_t unknown3;
+       union {
+               struct am7xxx_generic_header data;
+               struct am7xxx_devinfo_header devinfo;
+               struct am7xxx_image_header image;
+               struct am7xxx_power_header power;
+               struct am7xxx_zoom_header zoom;
+       } header_data;
+};
+
+
+#ifdef DEBUG
+static void debug_dump_devinfo_header(am7xxx_context *ctx, struct am7xxx_devinfo_header *d)
+{
+       if (ctx == NULL || d == NULL)
+               return;
+
+       debug(ctx, "Info header:\n");
+       debug(ctx, "\tnative_width:  0x%08x (%u)\n", d->native_width, d->native_width);
+       debug(ctx, "\tnative_height: 0x%08x (%u)\n", d->native_height, d->native_height);
+       debug(ctx, "\tunknown0:      0x%08x (%u)\n", d->unknown0, d->unknown0);
+       debug(ctx, "\tunknown1:      0x%08x (%u)\n", d->unknown1, d->unknown1);
+}
+
+static void debug_dump_image_header(am7xxx_context *ctx, struct am7xxx_image_header *i)
+{
+       if (ctx == NULL || i == NULL)
+               return;
+
+       debug(ctx, "Image header:\n");
+       debug(ctx, "\tformat:     0x%08x (%u)\n", i->format, i->format);
+       debug(ctx, "\twidth:      0x%08x (%u)\n", i->width, i->width);
+       debug(ctx, "\theight:     0x%08x (%u)\n", i->height, i->height);
+       debug(ctx, "\timage size: 0x%08x (%u)\n", i->image_size, i->image_size);
+}
+
+static void debug_dump_power_header(am7xxx_context *ctx, struct am7xxx_power_header *p)
 {
 {
-       if (i == NULL)
+       if (ctx == NULL || p == NULL)
                return;
 
                return;
 
-       printf("Image header:\n");
-       printf("format:      0x%08x (%u)\n", i->format, i->format);
-       printf("width:       0x%08x (%u)\n", i->width, i->width);
-       printf("height:      0x%08x (%u)\n", i->height, i->height);
-       printf("image size:  0x%08x (%u)\n", i->image_size, i->image_size);
+       debug(ctx, "Power header:\n");
+       debug(ctx, "\tbit2: 0x%08x (%u)\n", p->bit2, p->bit2);
+       debug(ctx, "\tbit1: 0x%08x (%u)\n", p->bit1, p->bit1);
+       debug(ctx, "\tbit0: 0x%08x (%u)\n", p->bit0, p->bit0);
 }
 
 }
 
-static void dump_header(struct am7xxx_header *h)
+static void debug_dump_zoom_header(am7xxx_context *ctx, struct am7xxx_zoom_header *z)
 {
 {
-       if (h == NULL)
+       if (ctx == NULL || z == NULL)
                return;
 
                return;
 
-       printf("packet_type:     0x%08x (%u)\n", h->packet_type, h->packet_type);
-       printf("unknown0:        0x%02hhx (%hhu)\n", h->unknown0, h->unknown0);
-       printf("header_data_len: 0x%02hhx (%hhu)\n", h->header_data_len, h->header_data_len);
-       printf("unknown2:        0x%02hhx (%hhu)\n", h->unknown2, h->unknown2);
-       printf("unknown3:        0x%02hhx (%hhu)\n", h->unknown3, h->unknown3);
+       debug(ctx, "Zoom header:\n");
+       debug(ctx, "\tbit1: 0x%08x (%u)\n", z->bit1, z->bit1);
+       debug(ctx, "\tbit0: 0x%08x (%u)\n", z->bit0, z->bit0);
+}
+
+static void debug_dump_header(am7xxx_context *ctx, struct am7xxx_header *h)
+{
+       if (ctx == NULL || h == NULL)
+               return;
+
+       debug(ctx, "BEGIN\n");
+       debug(ctx, "packet_type:     0x%08x (%u)\n", h->packet_type, h->packet_type);
+       debug(ctx, "direction:       0x%02hhx (%hhu) (%s)\n", h->direction, h->direction,
+             h->direction == AM7XXX_DIRECTION_IN ? "IN" :
+             h->direction == AM7XXX_DIRECTION_OUT ? "OUT" :
+             "UNKNOWN");
+       debug(ctx, "header_data_len: 0x%02hhx (%hhu)\n", h->header_data_len, h->header_data_len);
+       debug(ctx, "unknown2:        0x%02hhx (%hhu)\n", h->unknown2, h->unknown2);
+       debug(ctx, "unknown3:        0x%02hhx (%hhu)\n", h->unknown3, h->unknown3);
 
        switch(h->packet_type) {
 
        switch(h->packet_type) {
+       case AM7XXX_PACKET_TYPE_DEVINFO:
+               debug_dump_devinfo_header(ctx, &(h->header_data.devinfo));
+               break;
+
        case AM7XXX_PACKET_TYPE_IMAGE:
        case AM7XXX_PACKET_TYPE_IMAGE:
-               dump_image_header(&(h->header_data.image));
+               debug_dump_image_header(ctx, &(h->header_data.image));
+               break;
+
+       case AM7XXX_PACKET_TYPE_POWER:
+               debug_dump_power_header(ctx, &(h->header_data.power));
+               break;
+
+       case AM7XXX_PACKET_TYPE_ZOOM:
+               debug_dump_zoom_header(ctx, &(h->header_data.zoom));
                break;
 
        default:
                break;
 
        default:
-               printf("Packet type not supported!\n");
+               debug(ctx, "Packet type not supported!\n");
                break;
        }
                break;
        }
-
-       fflush(stdout);
+       debug(ctx, "END\n\n");
 }
 
 static inline unsigned int in_80chars(unsigned int i)
 {
 }
 
 static inline unsigned int in_80chars(unsigned int i)
 {
+       /* The 3 below is the length of "xx " where xx is the hex string
+        * representation of a byte */
        return ((i+1) % (80/3));
 }
 
        return ((i+1) % (80/3));
 }
 
-static void dump_buffer(uint8_t *buffer, unsigned int len)
+static void trace_dump_buffer(am7xxx_context *ctx, const char *message,
+                             uint8_t *buffer, unsigned int len)
 {
        unsigned int i;
 
 {
        unsigned int i;
 
-       if (buffer == NULL || len == 0)
+       if (ctx == NULL || buffer == NULL || len == 0)
                return;
 
                return;
 
+       trace(ctx, "\n");
+       if (message)
+               trace(ctx, "%s\n", message);
+
        for (i = 0; i < len; i++) {
        for (i = 0; i < len; i++) {
-               printf("%02hhX%c", buffer[i], (in_80chars(i) && (i < len - 1)) ? ' ' : '\n');
+               trace(ctx, "%02hhX%c", buffer[i], (in_80chars(i) && (i < len - 1)) ? ' ' : '\n');
        }
        }
-       fflush(stdout);
+       trace(ctx, "\n");
+}
+#else
+static void debug_dump_header(am7xxx_context *ctx, struct am7xxx_header *h)
+{
+       (void)ctx;
+       (void)h;
+}
+
+static void trace_dump_buffer(am7xxx_context *ctx, const char *message,
+                             uint8_t *buffer, unsigned int len)
+{
+       (void)ctx;
+       (void)message;
+       (void)buffer;
+       (void)len;
 }
 }
+#endif /* DEBUG */
 
 
-static int send_data(am7xxx_device dev, uint8_t *buffer, unsigned int len)
+static int read_data(am7xxx_device *dev, uint8_t *buffer, unsigned int len)
 {
        int ret;
 {
        int ret;
-       int transferred;
+       int transferred = 0;
 
 
-       dump_buffer(buffer, len);
+       ret = libusb_bulk_transfer(dev->usb_device, 0x81, buffer, len, &transferred, 0);
+       if (ret != 0 || (unsigned int)transferred != len) {
+               error(dev->ctx, "ret: %d\ttransferred: %d (expected %u)\n",
+                     ret, transferred, len);
+               return ret;
+       }
+
+       trace_dump_buffer(dev->ctx, "<-- received", buffer, len);
+
+       return 0;
+}
 
 
-       ret = libusb_bulk_transfer(dev, 1, buffer, len, &transferred, 0);
+static int send_data(am7xxx_device *dev, uint8_t *buffer, unsigned int len)
+{
+       int ret;
+       int transferred = 0;
+
+       trace_dump_buffer(dev->ctx, "sending -->", buffer, len);
+
+       ret = libusb_bulk_transfer(dev->usb_device, 0x1, buffer, len, &transferred, 0);
        if (ret != 0 || (unsigned int)transferred != len) {
        if (ret != 0 || (unsigned int)transferred != len) {
-               fprintf(stderr, "Error: ret: %d\ttransferred: %d (expected %u)\n",
-                       ret, transferred, len);
+               error(dev->ctx, "ret: %d\ttransferred: %d (expected %u)\n",
+                     ret, transferred, len);
                return ret;
        }
 
        return 0;
 }
 
                return ret;
        }
 
        return 0;
 }
 
-static int send_header(am7xxx_device dev, struct am7xxx_header *h)
+static void serialize_header(struct am7xxx_header *h, uint8_t *buffer)
 {
 {
-       union {
-               struct am7xxx_header header;
-               uint8_t buffer[sizeof (struct am7xxx_header)];
-       } data;
+       uint8_t **buffer_iterator = &buffer;
 
 
-       data.header = *h;
+       put_le32(h->packet_type, buffer_iterator);
+       put_8(h->direction, buffer_iterator);
+       put_8(h->header_data_len, buffer_iterator);
+       put_8(h->unknown2, buffer_iterator);
+       put_8(h->unknown3, buffer_iterator);
+       put_le32(h->header_data.data.field0, buffer_iterator);
+       put_le32(h->header_data.data.field1, buffer_iterator);
+       put_le32(h->header_data.data.field2, buffer_iterator);
+       put_le32(h->header_data.data.field3, buffer_iterator);
+}
+
+static void unserialize_header(uint8_t *buffer, struct am7xxx_header *h)
+{
+       uint8_t **buffer_iterator = &buffer;
 
 
-       return send_data(dev, data.buffer, sizeof (struct am7xxx_header));
+       h->packet_type = get_le32(buffer_iterator);
+       h->direction = get_8(buffer_iterator);
+       h->header_data_len = get_8(buffer_iterator);
+       h->unknown2 = get_8(buffer_iterator);
+       h->unknown3 = get_8(buffer_iterator);
+       h->header_data.data.field0 = get_le32(buffer_iterator);
+       h->header_data.data.field1 = get_le32(buffer_iterator);
+       h->header_data.data.field2 = get_le32(buffer_iterator);
+       h->header_data.data.field3 = get_le32(buffer_iterator);
 }
 
 }
 
-am7xxx_device am7xxx_init(void)
+static int read_header(am7xxx_device *dev, struct am7xxx_header *h)
 {
 {
-       am7xxx_device dev;
+       int ret;
 
 
-       libusb_init(NULL);
-       libusb_set_debug(NULL, 3);
+       ret = read_data(dev, dev->buffer, AM7XXX_HEADER_WIRE_SIZE);
+       if (ret < 0)
+               goto out;
 
 
-       dev = libusb_open_device_with_vid_pid(NULL,
-                                             AM7XXX_VENDOR_ID,
-                                             AM7XXX_PRODUCT_ID);
-       if (dev == NULL) {
+       unserialize_header(dev->buffer, h);
+
+       if (h->direction == AM7XXX_DIRECTION_IN) {
+               ret = 0;
+       } else {
+               error(dev->ctx,
+                     "Expected an AM7XXX_DIRECTION_IN packet, got one with direction = %d. Weird!\n",
+                     h->direction);
+               ret = -EINVAL;
+       }
+
+       debug_dump_header(dev->ctx, h);
+
+out:
+       return ret;
+}
+
+static int send_header(am7xxx_device *dev, struct am7xxx_header *h)
+{
+       int ret;
+
+       debug_dump_header(dev->ctx, h);
+
+       /* For symmetry with read_header() we should check here for
+        * h->direction == AM7XXX_DIRECTION_OUT but we just ensure that in all
+        * the callers and save some cycles here.
+        */
+
+       serialize_header(h, dev->buffer);
+
+       ret = send_data(dev, dev->buffer, AM7XXX_HEADER_WIRE_SIZE);
+       if (ret < 0)
+               error(dev->ctx, "failed to send data\n");
+
+       return ret;
+}
+
+/* When level == AM7XXX_LOG_FATAL do not check the log_level from the context
+ * and print the message unconditionally, this makes it possible to print
+ * fatal messages even early on initialization, before the context has been
+ * set up */
+static void log_message(am7xxx_context *ctx,
+                       int level,
+                       const char *function,
+                       int line,
+                       const char *fmt,
+                       ...)
+{
+       va_list ap;
+
+       if (level == AM7XXX_LOG_FATAL || (ctx && level <= ctx->log_level)) {
+               if (function) {
+                       fprintf(stderr, "%s", function);
+                       if (line)
+                               fprintf(stderr, "[%d]", line);
+                       fprintf(stderr, ": ");
+               }
+
+               va_start(ap, fmt);
+               vfprintf(stderr, fmt, ap);
+               va_end(ap);
+       }
+
+       return;
+}
+
+static am7xxx_device *add_new_device(am7xxx_context *ctx,
+                                    const struct am7xxx_usb_device_descriptor *desc)
+{
+       am7xxx_device **devices_list;
+       am7xxx_device *new_device;
+
+       if (ctx == NULL) {
+               fatal("context must not be NULL!\n");
+               return NULL;
+       }
+
+       new_device = malloc(sizeof(*new_device));
+       if (new_device == NULL) {
+               fatal("cannot allocate a new device (%s)\n", strerror(errno));
+               return NULL;
+       }
+       memset(new_device, 0, sizeof(*new_device));
+
+       new_device->ctx = ctx;
+       new_device->desc = desc;
+
+       devices_list = &(ctx->devices_list);
+
+       if (*devices_list == NULL) {
+               *devices_list = new_device;
+       } else {
+               am7xxx_device *prev = *devices_list;
+               while (prev->next)
+                       prev = prev->next;
+               prev->next = new_device;
+       }
+       return new_device;
+}
+
+static am7xxx_device *find_device(am7xxx_context *ctx,
+                                 unsigned int device_index)
+{
+       unsigned int i = 0;
+       am7xxx_device *current;
+
+       if (ctx == NULL) {
+               fatal("context must not be NULL!\n");
+               return NULL;
+       }
+
+       current = ctx->devices_list;
+       while (current && i++ < device_index)
+               current = current->next;
+
+       return current;
+}
+
+typedef enum {
+       SCAN_OP_BUILD_DEVLIST,
+       SCAN_OP_OPEN_DEVICE,
+} scan_op;
+
+/**
+ * This is where the central logic of multi-device support is.
+ *
+ * When 'op' == SCAN_OP_BUILD_DEVLIST the parameters 'open_device_index' and
+ * 'dev' are ignored; the function returns 0 on success and a negative value
+ * on error.
+ *
+ * When 'op' == SCAN_OP_OPEN_DEVICE the function opens the supported USB
+ * device with index 'open_device_index' and returns the correspondent
+ * am7xxx_device in the 'dev' parameter; the function returns 0 on success,
+ * 1 if the device was already open and a negative value on error.
+ *
+ * NOTES:
+ * if scan_devices() fails when called with 'op' == SCAN_OP_BUILD_DEVLIST,
+ * the caller might want to call am7xxx_shutdown() in order to remove
+ * devices possibly added before the failure.
+ */
+static int scan_devices(am7xxx_context *ctx, scan_op op,
+                       unsigned int open_device_index, am7xxx_device **dev)
+{
+       int num_devices;
+       libusb_device** list;
+       unsigned int current_index;
+       int i;
+       int ret;
+
+       if (ctx == NULL) {
+               fatal("context must not be NULL!\n");
+               return -EINVAL;
+       }
+       if (op == SCAN_OP_BUILD_DEVLIST && ctx->devices_list != NULL) {
+               error(ctx, "device scan done already? Abort!\n");
+               return -EINVAL;
+       }
+
+       num_devices = libusb_get_device_list(ctx->usb_context, &list);
+       if (num_devices < 0) {
+               ret = -ENODEV;
+               goto out;
+       }
+
+       current_index = 0;
+       for (i = 0; i < num_devices; i++) {
+               struct libusb_device_descriptor desc;
+               unsigned int j;
+
+               ret = libusb_get_device_descriptor(list[i], &desc);
+               if (ret < 0)
+                       continue;
+
+               for (j = 0; j < ARRAY_SIZE(supported_devices); j++) {
+                       if (desc.idVendor == supported_devices[j].vendor_id &&
+                           desc.idProduct == supported_devices[j].product_id) {
+
+                               if (op == SCAN_OP_BUILD_DEVLIST) {
+                                       am7xxx_device *new_device;
+                                       info(ctx, "am7xxx device found, index: %d, name: %s\n",
+                                            current_index,
+                                            supported_devices[j].name);
+                                       new_device = add_new_device(ctx, &supported_devices[j]);
+                                       if (new_device == NULL) {
+                                               /* XXX, the caller may want
+                                                * to call am7xxx_shutdown() if
+                                                * we fail here, as we may have
+                                                * added some devices already
+                                                */
+                                               debug(ctx, "Cannot create a new device\n");
+                                               ret = -ENODEV;
+                                               goto out;
+                                       }
+                               } else if (op == SCAN_OP_OPEN_DEVICE &&
+                                          current_index == open_device_index) {
+
+                                       *dev = find_device(ctx, open_device_index);
+                                       if (*dev == NULL) {
+                                               ret = -ENODEV;
+                                               goto out;
+                                       }
+
+                                       /* the usb device has already been opened */
+                                       if ((*dev)->usb_device) {
+                                               debug(ctx, "(*dev)->usb_device already set\n");
+                                               ret = 1;
+                                               goto out;
+                                       }
+
+                                       ret = libusb_open(list[i], &((*dev)->usb_device));
+                                       if (ret < 0) {
+                                               debug(ctx, "libusb_open failed\n");
+                                               goto out;
+                                       }
+
+                                       /* XXX, the device is now open, if any
+                                        * of the calls below fail we need to
+                                        * close it again before bailing out.
+                                        */
+
+                                       ret = libusb_set_configuration((*dev)->usb_device,
+                                                                      (*dev)->desc->configuration);
+                                       if (ret < 0) {
+                                               debug(ctx, "libusb_set_configuration failed\n");
+                                               debug(ctx, "Cannot set configuration %hhu\n",
+                                                     (*dev)->desc->configuration);
+                                               goto out_libusb_close;
+                                       }
+
+                                       ret = libusb_claim_interface((*dev)->usb_device,
+                                                                    (*dev)->desc->interface_number);
+                                       if (ret < 0) {
+                                               debug(ctx, "libusb_claim_interface failed\n");
+                                               debug(ctx, "Cannot claim interface %hhu\n",
+                                                     (*dev)->desc->interface_number);
+out_libusb_close:
+                                               libusb_close((*dev)->usb_device);
+                                               (*dev)->usb_device = NULL;
+                                               goto out;
+                                       }
+
+                                       goto out;
+                               }
+                               current_index++;
+                       }
+               }
+       }
+
+       /* if we made it up to here we didn't find any device to open */
+       if (op == SCAN_OP_OPEN_DEVICE) {
+               error(ctx, "Cannot find any device to open\n");
+               ret = -ENODEV;
+               goto out;
+       }
+
+       /* everything went fine when building the device list */
+       ret = 0;
+out:
+       libusb_free_device_list(list, 1);
+       return ret;
+}
+
+/* Public API */
+
+AM7XXX_PUBLIC int am7xxx_init(am7xxx_context **ctx)
+{
+       int ret = 0;
+
+       *ctx = malloc(sizeof(**ctx));
+       if (*ctx == NULL) {
+               fatal("cannot allocate the context (%s)\n", strerror(errno));
+               ret = -ENOMEM;
+               goto out;
+       }
+       memset(*ctx, 0, sizeof(**ctx));
+
+       /* Set the highest log level during initialization */
+       (*ctx)->log_level = AM7XXX_LOG_TRACE;
+
+       ret = libusb_init(&((*ctx)->usb_context));
+       if (ret < 0)
+               goto out_free_context;
+
+       libusb_set_debug((*ctx)->usb_context, 3);
+
+       ret = scan_devices(*ctx, SCAN_OP_BUILD_DEVLIST , 0, NULL);
+       if (ret < 0) {
+               error(*ctx, "scan_devices() failed\n");
+               am7xxx_shutdown(*ctx);
+               goto out;
+       }
+
+       /* Set a quieter log level as default for normal operation */
+       (*ctx)->log_level = AM7XXX_LOG_ERROR;
+       return 0;
+
+out_free_context:
+       free(*ctx);
+       *ctx = NULL;
+out:
+       return ret;
+}
+
+AM7XXX_PUBLIC void am7xxx_shutdown(am7xxx_context *ctx)
+{
+       am7xxx_device *current;
+
+       if (ctx == NULL) {
+               fatal("context must not be NULL!\n");
+               return;
+       }
+
+       current = ctx->devices_list;
+       while (current) {
+               am7xxx_device *next = current->next;
+               am7xxx_close_device(current);
+               free(current->device_info);
+               free(current);
+               current = next;
+       }
+
+       libusb_exit(ctx->usb_context);
+       free(ctx);
+       ctx = NULL;
+}
+
+AM7XXX_PUBLIC void am7xxx_set_log_level(am7xxx_context *ctx, am7xxx_log_level log_level)
+{
+       ctx->log_level = log_level;
+}
+
+AM7XXX_PUBLIC int am7xxx_open_device(am7xxx_context *ctx, am7xxx_device **dev,
+                      unsigned int device_index)
+{
+       int ret;
+
+       if (ctx == NULL) {
+               fatal("context must not be NULL!\n");
+               return -EINVAL;
+       }
+
+       ret = scan_devices(ctx, SCAN_OP_OPEN_DEVICE, device_index, dev);
+       if (ret < 0) {
                errno = ENODEV;
                errno = ENODEV;
-               perror("libusb_open_device_with_vid_pid");
-               goto out_libusb_exit;
+               goto out;
+       } else if (ret > 0) {
+               warning(ctx, "device %d already open\n", device_index);
+               errno = EBUSY;
+               ret = -EBUSY;
+               goto out;
        }
 
        }
 
-       libusb_set_configuration(dev, 1);
-       libusb_claim_interface(dev, 0);
+       /* Philips/Sagemcom PicoPix projectors require that the DEVINFO packet
+        * is the first one to be sent to the device in order for it to
+        * successfully return the correct device information.
+        *
+        * So, if there is not a cached version of it (from a previous open),
+        * we ask for device info at open time,
+        */
+       if ((*dev)->device_info == NULL) {
+               ret = am7xxx_get_device_info(*dev, NULL);
+               if (ret < 0)
+                       error(ctx, "cannot get device info\n");
+       }
 
 
-       return dev;
+out:
+       return ret;
+}
 
 
-out_libusb_exit:
-       libusb_exit(NULL);
-       return NULL;
+AM7XXX_PUBLIC int am7xxx_close_device(am7xxx_device *dev)
+{
+       if (dev == NULL) {
+               fatal("dev must not be NULL!\n");
+               return -EINVAL;
+       }
+       if (dev->usb_device) {
+               libusb_release_interface(dev->usb_device, dev->desc->interface_number);
+               libusb_close(dev->usb_device);
+               dev->usb_device = NULL;
+       }
+       return 0;
 }
 
 }
 
-void am7xxx_shutdown(am7xxx_device dev)
+AM7XXX_PUBLIC int am7xxx_get_device_info(am7xxx_device *dev,
+                          am7xxx_device_info *device_info)
 {
 {
-       if (dev) {
-               libusb_close(dev);
-               libusb_exit(NULL);
+       int ret;
+       struct am7xxx_header h = {
+               .packet_type     = AM7XXX_PACKET_TYPE_DEVINFO,
+               .direction       = AM7XXX_DIRECTION_OUT,
+               .header_data_len = 0x00,
+               .unknown2        = 0x3e,
+               .unknown3        = 0x10,
+               .header_data = {
+                       .devinfo = {
+                               .native_width  = 0,
+                               .native_height = 0,
+                               .unknown0      = 0,
+                               .unknown1      = 0,
+                       },
+               },
+       };
+
+       if (dev->device_info) {
+               memcpy(device_info, dev->device_info, sizeof(*device_info));
+               return 0;
+       }
+
+       ret = send_header(dev, &h);
+       if (ret < 0)
+               return ret;
+
+       ret = read_header(dev, &h);
+       if (ret < 0)
+               return ret;
+
+       if (h.packet_type != AM7XXX_PACKET_TYPE_DEVINFO) {
+               error(dev->ctx, "expected packet type: %d, got %d instead!\n",
+                     AM7XXX_PACKET_TYPE_DEVINFO, h.packet_type);
+               errno = ENOTSUP;
+               return -ENOTSUP;
        }
        }
+
+       dev->device_info = malloc(sizeof(*dev->device_info));
+       if (dev->device_info == NULL) {
+               error(dev->ctx, "cannot allocate a device info (%s)\n",
+                      strerror(errno));
+               return -ENOMEM;
+       }
+       memset(dev->device_info, 0, sizeof(*dev->device_info));
+
+       dev->device_info->native_width = h.header_data.devinfo.native_width;
+       dev->device_info->native_height = h.header_data.devinfo.native_height;
+#if 0
+       /* No reason to expose these in the public API until we know what they mean */
+       dev->device_info->unknown0 = h.header_data.devinfo.unknown0;
+       dev->device_info->unknown1 = h.header_data.devinfo.unknown1;
+#endif
+
+       return 0;
+}
+
+AM7XXX_PUBLIC int am7xxx_calc_scaled_image_dimensions(am7xxx_device *dev,
+                                       unsigned int upscale,
+                                       unsigned int original_width,
+                                       unsigned int original_height,
+                                       unsigned int *scaled_width,
+                                       unsigned int *scaled_height)
+{
+
+       am7xxx_device_info device_info;
+       float width_ratio;
+       float height_ratio;
+       int ret;
+
+       ret = am7xxx_get_device_info(dev, &device_info);
+       if (ret < 0) {
+               error(dev->ctx, "cannot get device info\n");
+               return ret;
+       }
+
+       /*
+        * Check if we need to rescale; if the input image fits the native
+        * dimensions there is no need to, unless we want to upscale.
+        */
+       if (!upscale &&
+           original_width <= device_info.native_width &&
+           original_height <= device_info.native_height ) {
+               debug(dev->ctx, "CASE 0, no rescaling, the original image fits already\n");
+               *scaled_width = original_width;
+               *scaled_height = original_height;
+               return 0;
+       }
+
+       /* Input dimensions relative to the device native dimensions */
+       width_ratio =  (float)original_width / device_info.native_width;
+       height_ratio = (float)original_height / device_info.native_height;
+
+       if (width_ratio > height_ratio) {
+               /*
+                * The input is proportionally "wider" than the device viewport
+                * so its height needs to be adjusted
+                */
+               debug(dev->ctx, "CASE 1, original image wider, adjust the scaled height\n");
+               *scaled_width = device_info.native_width;
+               *scaled_height = (unsigned int)lroundf(original_height / width_ratio);
+       } else if (width_ratio < height_ratio) {
+               /*
+                * The input is proportionally "taller" than the device viewport
+                * so its width needs to be adjusted
+                */
+               debug(dev->ctx, "CASE 2 original image taller, adjust the scaled width\n");
+               *scaled_width = (unsigned int)lroundf(original_width / height_ratio);
+               *scaled_height = device_info.native_height;
+       } else {
+               debug(dev->ctx, "CASE 3, just rescale, same aspect ratio already\n");
+               *scaled_width = device_info.native_width;
+               *scaled_height = device_info.native_height;
+       }
+       debug(dev->ctx, "scaled dimensions: %dx%d\n", *scaled_width, *scaled_height);
+
+       return 0;
 }
 
 }
 
-int am7xxx_send_image(am7xxx_device dev,
+AM7XXX_PUBLIC int am7xxx_send_image(am7xxx_device *dev,
                      am7xxx_image_format format,
                      unsigned int width,
                      unsigned int height,
                      uint8_t *image,
                      am7xxx_image_format format,
                      unsigned int width,
                      unsigned int height,
                      uint8_t *image,
-                     unsigned int size)
+                     unsigned int image_size)
 {
        int ret;
        struct am7xxx_header h = {
 {
        int ret;
        struct am7xxx_header h = {
-               .packet_type     = htole32(AM7XXX_PACKET_TYPE_IMAGE),
-               .unknown0        = 0x00,
+               .packet_type     = AM7XXX_PACKET_TYPE_IMAGE,
+               .direction       = AM7XXX_DIRECTION_OUT,
                .header_data_len = sizeof(struct am7xxx_image_header),
                .unknown2        = 0x3e,
                .unknown3        = 0x10,
                .header_data = {
                        .image = {
                .header_data_len = sizeof(struct am7xxx_image_header),
                .unknown2        = 0x3e,
                .unknown3        = 0x10,
                .header_data = {
                        .image = {
-                               .format     = htole32(format),
-                               .width      = htole32(width),
-                               .height     = htole32(height),
-                               .image_size = htole32(size),
+                               .format     = format,
+                               .width      = width,
+                               .height     = height,
+                               .image_size = image_size,
                        },
                },
        };
 
                        },
                },
        };
 
-       dump_header(&h);
-       printf("\n");
+       ret = send_header(dev, &h);
+       if (ret < 0)
+               return ret;
+
+       if (image == NULL || image_size == 0) {
+               warning(dev->ctx, "Not sending any data, check the 'image' or 'image_size' parameters\n");
+               return 0;
+       }
+
+       return send_data(dev, image, image_size);
+}
+
+AM7XXX_PUBLIC int am7xxx_set_power_mode(am7xxx_device *dev, am7xxx_power_mode power)
+{
+       int ret;
+       struct am7xxx_header h = {
+               .packet_type     = AM7XXX_PACKET_TYPE_POWER,
+               .direction       = AM7XXX_DIRECTION_OUT,
+               .header_data_len = sizeof(struct am7xxx_power_header),
+               .unknown2        = 0x3e,
+               .unknown3        = 0x10,
+       };
+
+       switch(power) {
+       case AM7XXX_POWER_OFF:
+               h.header_data.power.bit2 = 0;
+               h.header_data.power.bit1 = 0;
+               h.header_data.power.bit0 = 0;
+               break;
 
 
-       printf("Dump Buffers\n");
-       dump_buffer(reference_image_header, sizeof(struct am7xxx_header));
+       case AM7XXX_POWER_LOW:
+               h.header_data.power.bit2 = 0;
+               h.header_data.power.bit1 = 0;
+               h.header_data.power.bit0 = 1;
+               break;
+
+       case AM7XXX_POWER_MIDDLE:
+               h.header_data.power.bit2 = 0;
+               h.header_data.power.bit1 = 1;
+               h.header_data.power.bit0 = 0;
+               break;
+
+       case AM7XXX_POWER_HIGH:
+               h.header_data.power.bit2 = 0;
+               h.header_data.power.bit1 = 1;
+               h.header_data.power.bit0 = 1;
+               break;
+
+       case AM7XXX_POWER_TURBO:
+               h.header_data.power.bit2 = 1;
+               h.header_data.power.bit1 = 0;
+               h.header_data.power.bit0 = 0;
+               break;
+
+       default:
+               error(dev->ctx, "Unsupported power mode.\n");
+               return -EINVAL;
+       };
 
        ret = send_header(dev, &h);
        if (ret < 0)
                return ret;
 
 
        ret = send_header(dev, &h);
        if (ret < 0)
                return ret;
 
-       if (image == NULL || size == 0)
-               return 0;
+       return 0;
+}
 
 
-       return send_data(dev, image, size);
+AM7XXX_PUBLIC int am7xxx_set_zoom_mode(am7xxx_device *dev, am7xxx_zoom_mode zoom)
+{
+       int ret;
+       struct am7xxx_header h = {
+               .packet_type     = AM7XXX_PACKET_TYPE_ZOOM,
+               .direction       = AM7XXX_DIRECTION_OUT,
+               .header_data_len = sizeof(struct am7xxx_zoom_header),
+               .unknown2        = 0x3e,
+               .unknown3        = 0x10,
+       };
+
+       switch(zoom) {
+       case AM7XXX_ZOOM_ORIGINAL:
+               h.header_data.zoom.bit1 = 0;
+               h.header_data.zoom.bit0 = 0;
+               break;
+
+       case AM7XXX_ZOOM_H:
+               h.header_data.zoom.bit1 = 0;
+               h.header_data.zoom.bit0 = 1;
+               break;
+
+       case AM7XXX_ZOOM_H_V:
+               h.header_data.zoom.bit1 = 1;
+               h.header_data.zoom.bit0 = 0;
+               break;
+
+       case AM7XXX_ZOOM_TEST:
+               h.header_data.zoom.bit1 = 1;
+               h.header_data.zoom.bit0 = 1;
+               break;
+
+       default:
+               error(dev->ctx, "Unsupported zoom mode.\n");
+               return -EINVAL;
+       };
+
+       ret = send_header(dev, &h);
+       if (ret < 0)
+               return ret;
+
+       return 0;
 }
 }