SH7265 Datasheet, PDF (1522/2024 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperHTM RISC engine Family / SH7260 Series

Section 28 2D Graphics Engine (2DG)
The blending processor in the blitter, which performs pseudo-anti-aliasing with characters, blends
characters having an arbitrary α value with an α value = 1 graphic in a rectangular region, and it
can transfer the results to the output plane by converting the blending results to an arbitrary α
value (register value) for blending with the moving pictures. In this case, the blending results
between characters and graphics will be:
Cgout = αmCm + (1 − αm) Cz, αgout = 1
Further, if global α (the BRDC_A bit of the GR_BRDCOL register) is selected using the
subsequent stage global α selection bit (the GALFA bit of the GR_BRD1CNT register), the results
that are output from the blending processor in the blitter will be:
Cgout = αmCm + (1 − αm) Cz, αgout = αdc = BRDC_A bit of GR_BRDCOL register
Thus, pixels having αdc values are created in the output plane.
In terms of the 2DG, if synthesis using two planes is performed by blending in the blitter and all
color values of the output plane are α-value-computed (i.e., weighted) data, the blending between
the moving picture and the output plane in the output block will be performed by selecting
premultiplied in the blending processor in the output block. On the other hand, if the color values
on the output plane are not α-weighted, the blending between the moving picture and the output
plane in the output block will be performed by selecting non-premultiplied in the blending
processor in the output block.
Figure 28.23 shows a summary of operations during blending, as follows:
(1) If GCOLR bit in GR_BRD1CNT register = 0, selects data from the SA buffer.
If GCOLR bit in GR_BRD1CNT register = 1, selects the value of the GR_BRDCOL register.
In fill mode, the value in the GR_BRDCOL register is selected in the same way as if the
GCOLR bit of the GR_BRD1CNT register was set (1). However, the value of the GCOLR bit
does not change at this time.
(2) Blends the data selected in Step 1 above with the data from the SB buffer selected on the basis
of the SBSEL bit of the GR_BLTMODE register.
(3) Of the data blended in Step 2 above, the color value Cout is output to the DC buffer as is. With
regard to the α value α out, the blended α value is output to the DC buffer as is, provided the
GALFA bit of the GR_BRD1CNT register = 0. If the GALFA bit of the GR_BRD1CNT
register = 1, the AFTER_A bit value of the GR_BRD1CNT register is output to the DC buffer.
Rev. 1.00 Mar. 14, 2008 Page 1486 of 1984
REJ09B0351-0100