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SCSIVideo: Add video mirroring device
Receives raw 1bpp screen data as a WRITE(10) command and displays it on the Raspberry Pi's framebuffer. This is setup for reading and displaying a compact Mac's 1bpp 512x342 display, but the depth and screen size should probably come from a SCSI message sent by the remote end during a setup phase. Some high-resolution logging shows it taking about 83 milliseconds to receive the 21888 bytes of data through SCSI, and about 3 milliseconds to convert it and draw it on the framebuffer.
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,170 @@ | ||
| //--------------------------------------------------------------------------- | ||
| // | ||
| // SCSI Video Mirror for Raspberry Pi | ||
| // | ||
| // Copyright (C) 2020 joshua stein <jcs@jcs.org> | ||
| // | ||
| // Licensed under the BSD 3-Clause License. | ||
| // See LICENSE file in the project root folder. | ||
| // | ||
| //--------------------------------------------------------------------------- | ||
|
|
||
| #include "scsi_video.h" | ||
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| #include <err.h> | ||
| #include <fcntl.h> | ||
| #include <linux/fb.h> | ||
|
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| static unsigned char reverse_table[256]; | ||
|
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| SCSIVideo::SCSIVideo() : Disk() | ||
| { | ||
| struct fb_var_screeninfo fbinfo; | ||
| struct fb_fix_screeninfo fbfixinfo; | ||
|
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||
| disk.id = MAKEID('S', 'C', 'V', 'D'); | ||
|
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| // create lookup table | ||
| for (int i = 0; i < 256; i++) { | ||
| unsigned char b = i; | ||
| b = (b & 0xF0) >> 4 | (b & 0x0F) << 4; | ||
| b = (b & 0xCC) >> 2 | (b & 0x33) << 2; | ||
| b = (b & 0xAA) >> 1 | (b & 0x55) << 1; | ||
| reverse_table[i] = b; | ||
| } | ||
|
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| // TODO: receive these through a SCSI message sent by the remote | ||
| this->screen_width = 512; | ||
| this->screen_height = 342; | ||
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| this->fbfd = open("/dev/fb0", O_RDWR); | ||
| if (this->fbfd == -1) | ||
| err(1, "open /dev/fb0"); | ||
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| if (ioctl(this->fbfd, FBIOGET_VSCREENINFO, &fbinfo)) | ||
| err(1, "ioctl FBIOGET_VSCREENINFO"); | ||
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| if (ioctl(this->fbfd, FBIOGET_FSCREENINFO, &fbfixinfo)) | ||
| err(1, "ioctl FBIOGET_FSCREENINFO"); | ||
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| if (fbinfo.bits_per_pixel != 32) | ||
| errx(1, "TODO: support %d bpp", fbinfo.bits_per_pixel); | ||
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| this->fbwidth = fbinfo.xres; | ||
| this->fbheight = fbinfo.yres; | ||
| this->fbbpp = fbinfo.bits_per_pixel; | ||
| this->fblinelen = fbfixinfo.line_length; | ||
| this->fbsize = fbfixinfo.smem_len; | ||
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| printf("SCSIVideo drawing on %dx%d %d bpp framebuffer\n", | ||
| this->fbwidth, this->fbheight, this->fbbpp); | ||
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| this->fb = (char *)mmap(0, this->fbsize, PROT_READ | PROT_WRITE, MAP_SHARED, | ||
| this->fbfd, 0); | ||
| if ((int)this->fb == -1) | ||
| err(1, "mmap"); | ||
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| memset(this->fb, 0, this->fbsize); | ||
| } | ||
|
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| //--------------------------------------------------------------------------- | ||
| // | ||
| // Destructor | ||
| // | ||
| //--------------------------------------------------------------------------- | ||
| SCSIVideo::~SCSIVideo() | ||
| { | ||
| munmap(this->fb, this->fbsize); | ||
| close(this->fbfd); | ||
| } | ||
|
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| //--------------------------------------------------------------------------- | ||
| // | ||
| // INQUIRY | ||
| // | ||
| //--------------------------------------------------------------------------- | ||
| int FASTCALL SCSIVideo::Inquiry( | ||
| const DWORD *cdb, BYTE *buf, DWORD major, DWORD minor) | ||
| { | ||
| int size; | ||
|
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| ASSERT(this); | ||
| ASSERT(cdb); | ||
| ASSERT(buf); | ||
| ASSERT(cdb[0] == 0x12); | ||
|
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| // EVPD check | ||
| if (cdb[1] & 0x01) { | ||
| disk.code = DISK_INVALIDCDB; | ||
| return FALSE; | ||
| } | ||
|
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| // Basic data | ||
| // buf[0] ... Communication Device | ||
| // buf[2] ... SCSI-2 compliant command system | ||
| // buf[3] ... SCSI-2 compliant Inquiry response | ||
| // buf[4] ... Inquiry additional data | ||
| memset(buf, 0, 8); | ||
| buf[0] = 0x09; | ||
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| // SCSI-2 p.104 4.4.3 Incorrect logical unit handling | ||
| if (((cdb[1] >> 5) & 0x07) != disk.lun) { | ||
| buf[0] = 0x7f; | ||
| } | ||
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| buf[2] = 0x02; | ||
| buf[3] = 0x02; | ||
| buf[4] = 36 - 5 + 8; // required + 8 byte extension | ||
|
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| // Fill with blanks | ||
| memset(&buf[8], 0x20, buf[4] - 3); | ||
|
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| // Vendor name | ||
| memcpy(&buf[8], "jcs", 3); | ||
|
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| // Product name | ||
| memcpy(&buf[16], "video mirror", 12); | ||
|
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| // Revision | ||
| memcpy(&buf[32], "1337", 4); | ||
|
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| // Optional function valid flag | ||
| buf[36] = '0'; | ||
|
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| // Size of data that can be returned | ||
| size = (buf[4] + 5); | ||
|
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| // Limit if the other buffer is small | ||
| if (size > (int)cdb[4]) { | ||
| size = (int)cdb[4]; | ||
| } | ||
|
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| // Success | ||
| disk.code = DISK_NOERROR; | ||
| return size; | ||
| } | ||
|
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| BOOL FASTCALL SCSIVideo::ReceiveBuffer(int len, BYTE *buffer) | ||
| { | ||
| int row = 0; | ||
| int col = 0; | ||
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| for (int i = 0; i < len; i++) { | ||
| unsigned char j = reverse_table[buffer[i]]; | ||
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| for (int bit = 0; bit < 8; bit++) { | ||
| int loc = (col * (this->fbbpp / 8)) + (row * this->fblinelen); | ||
| col++; | ||
| if (col % this->screen_width == 0) { | ||
| col = 0; | ||
| row++; | ||
| } | ||
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| *(this->fb + loc) = (j & (1 << bit)) ? 0 : 255; | ||
| *(this->fb + loc + 1) = (j & (1 << bit)) ? 0 : 255; | ||
| *(this->fb + loc + 2) = (j & (1 << bit)) ? 0 : 255; | ||
| } | ||
| } | ||
|
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| return TRUE; | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,37 @@ | ||
| //--------------------------------------------------------------------------- | ||
| // | ||
| // SCSI Video Mirror for Raspberry Pi | ||
| // | ||
| // Copyright (C) 2020 joshua stein <jcs@jcs.org> | ||
| // | ||
| // Licensed under the BSD 3-Clause License. | ||
| // See LICENSE file in the project root folder. | ||
| // | ||
| //--------------------------------------------------------------------------- | ||
|
|
||
| #pragma once | ||
|
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| #include "os.h" | ||
| #include "disk.h" | ||
|
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| class SCSIVideo : public Disk | ||
| { | ||
| public: | ||
| SCSIVideo(); | ||
| virtual ~SCSIVideo(); | ||
|
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| int FASTCALL Inquiry(const DWORD *cdb, BYTE *buf, DWORD major, DWORD minor); | ||
| BOOL FASTCALL ReceiveBuffer(int len, BYTE *buffer); | ||
|
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| private: | ||
| int screen_width; | ||
| int screen_height; | ||
|
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| int fbfd; | ||
| char *fb; | ||
| int fbwidth; | ||
| int fbheight; | ||
| int fblinelen; | ||
| int fbsize; | ||
| int fbbpp; | ||
| }; |
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