mirror of https://github.com/nmlgc/ReC98.git
67 lines
1.7 KiB
C++
67 lines
1.7 KiB
C++
#include "platform.h"
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#include "x86real.h"
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#include "planar.h"
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#include "shiftjis.hpp"
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#include "platform/x86real/pc98/font.hpp"
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// The PC-98 character generator can be accessed in two ways:
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//
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// 1) I/O ports (0xA1, 0xA3, 0xA5, 0xA9)
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// 2) BIOS function INT 18h AH=14h (reading) / AH=18h (writing gaiji)
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//
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// The BIOS variant is both simpler to use *and* faster, as the BIOS implements
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// it in the optimal way for the specific hardware we run on:
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//
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// • At worst, it's an optimized ASM version of the I/O port code we would
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// write ourselves (as seen in the PC-9801VX / PC-9801RA BIOS).
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// • At best, it directly reads from and writes to memory after mapping the JIS
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// code point to an address, which is always preferable to port I/O (as seen
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// in the PC-98HA BIOS).
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// • Emulators directly implement it in native code.
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void font_read(font_glyph_t& glyph, jis_t jis)
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{
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_BX = FP_SEG(&glyph);
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_CX = FP_OFF(&glyph);
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_DX = jis;
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_AH = 0x14;
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geninterrupt(0x18);
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glyph.tag.w *= GLYPH_HALF_W;
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glyph.tag.h *= GLYPH_HALF_H;
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}
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void font_read(font_glyph_ank_8x8_t& glyph, ank_t ank)
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{
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font_read(reinterpret_cast<font_glyph_t &>(glyph), static_cast<jis_t>(ank));
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}
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void font_read(font_glyph_ank_8x16_t& glyph, ank_t ank)
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{
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font_read(reinterpret_cast<font_glyph_t &>(glyph), (0x8000 + ank));
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}
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void font_gaiji_write(
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const dot_rect_t(GLYPH_FULL_W, GLYPH_H)* gaiji,
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uint16_t count,
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uint8_t id
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)
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{
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// Yeah, that copy is kind of silly, but we don't want to force that
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// awkward 16×17 format onto the caller.
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font_glyph_kanji_t tmp;
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jis_t jis = (0x7680 + id);
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for(uint16_t i = 0; i < count; i++) {
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tmp.dots = *gaiji;
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_BX = FP_SEG(&tmp);
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_CX = FP_OFF(&tmp);
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_DX = jis;
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_DX &= 0xFF7F;
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_AH = 0x1A;
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geninterrupt(0x18);
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gaiji++;
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jis++;
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}
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}
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