PATCH: Framebuffer for C123 and C155

[Christian Vogel]

Two things I did want to mention, but forgot to write in my first
email are:

(1) For future work, it should be attempted to call the
    synchronisation of the framebuffer memory and the LC display
    in a low-priority task or timer so that the fb_flush() method
    that blocks on updates is no longer necessary

(2) The price we pay for having the framebuffer, in terms of object-size,
    is detailed below, by comparing the original version of hello_world
    with the "new and improved" framebuffer.

Comparing hello world before/after transition to framebuffer code.

For hello world on E88 (C123) (with HelvR08 and HelvB14 fonts):

	.text    +1696 byte  (grows from 0x3fd0 - 0x3930)
	.rodata   +944 byte  (0xc76 - 0x1026)
	.data      +80 byte  (0x15c - 0x10c)
	.bss      +860 byte  (0x4470 - 0x47cc)

For hello world on E99 (C155) (w/ HelvR08, HelvB14):

	.text     +1344 byte
	.rodata   +1088 byte
	.data       +80 byte
	.bss      +6564 byte

Generally .rodata is mostly due to font data, .bss is our
in-ram framebuffer. .text increase is due to the code for
character- and box drawing.

Individual sizes:

$ /usr/opt/arm-gcc/bin/arm-elf-size *.o         
   text    data     bss     dec     hex filename
   1873       0       0    1873     751 fb_bw8.o	(C123      )
   1764       0       0    1764     6e4 fb_rgb332.o	(      C155)
    706      72    6568    7346    1cb2 fb_ssd1783.o	(      C155)
    328      72     864    1264     4f0 fb_st7558.o	(C123      )
     76       8       0      84      54 font.o		(C123, C155)
      0       0       0       0       0 framebuffer.o	(C123, C155)
   1804       0       0    1804     70c helvB14.o	(C123, C155)
   1212       0       0    1212     4bc helvR08.o	(C128, C155)

(Currently unused, optional further fonts:)
     60      56       0     116      74 fb_dummy.o
   1220       0       0    1220     4c4 helvB08.o
   3548       0       0    3548     ddc helvB24.o
   3480       0       0    3480     d98 helvR24.o
   1116       0       0    1116     45c 4x6.o
   1188       0       0    1188     4a4 5x8.o

Old display code (everything compiled in for all mobiles):
     88       0       0      88      58 display.o
   2048       0       0    2048     800 font_r8x8_horiz.o
   2048       0       0    2048     800 font_r8x8.o
    920       0       0     920     398 ssd1783.o
    399       0       0     399     18f st7558.o
    638       0       0     638     27e td014.o