Eremey Valetov
4551c88a50
BSAVE/BLOAD: save and load virtual memory blocks with 0xFD-header binary format, operating on the current DEF SEG segment. TUI color: tui_refresh emits ANSI SGR codes from cell attributes; COLOR statement sets tui.current_attr when TUI is active. Extended PEEK/POKE: CGA graphics framebuffer (interlaced layout) via gfx_cga_peek/poke routed through virmem when gfx_active(); BIOS keyboard shift flags (offset 0x17 bit 7 = insert mode). Add bibliography to language reference. 64 tests, all passing.
140 lines
3.4 KiB
C
140 lines
3.4 KiB
C
#include "virmem.h"
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#include "tui.h"
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#include "graphics.h"
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#include <time.h>
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/*
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* BIOS data area emulation (segment 0x0040).
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*
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* Real addresses we care about:
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* 0040:0017 Keyboard shift flags byte 1
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* 0040:0018 Keyboard shift flags byte 2
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* 0040:0049 Current video mode
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* 0040:004A Number of screen columns (word)
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* 0040:0050 Cursor position page 0 (col, row)
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* 0040:006C Timer tick count (dword, ~18.2 Hz)
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* 0040:0084 Rows on screen minus 1
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*/
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static uint8_t bios_peek(uint16_t offset)
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{
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switch (offset) {
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case 0x17:
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/* Bit 7 = insert mode; other modifier bits not detectable on POSIX */
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return tui.insert_mode ? 0x80 : 0;
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case 0x18:
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return 0;
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case 0x49:
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/* Current video mode: 3 = 80x25 color text, 1 = 320x200, 2 = 640x200 */
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return gfx_active() ? (uint8_t)gfx_get_mode() : 3;
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case 0x4A:
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return tui.active ? (uint8_t)tui.cols : 80;
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case 0x4B:
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return 0; /* high byte of column count */
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case 0x50:
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return tui.active ? (uint8_t)tui.cursor_col : 0;
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case 0x51:
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return tui.active ? (uint8_t)tui.cursor_row : 0;
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case 0x6C: case 0x6D: case 0x6E: case 0x6F: {
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/* Timer ticks since midnight (~18.2065 Hz) */
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struct timespec ts;
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clock_gettime(CLOCK_REALTIME, &ts);
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struct tm tm;
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localtime_r(&ts.tv_sec, &tm);
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long secs = tm.tm_hour * 3600L + tm.tm_min * 60L + tm.tm_sec;
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uint32_t ticks = (uint32_t)(secs * 18.2065 + ts.tv_nsec / 54925400.0);
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return (ticks >> ((offset - 0x6C) * 8)) & 0xFF;
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}
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case 0x84:
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return tui.active ? (uint8_t)(tui.rows - 1) : 24;
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default:
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return 0;
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}
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}
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static void bios_poke(uint16_t offset, uint8_t value)
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{
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(void)offset;
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(void)value;
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/* BIOS data area writes are silently ignored */
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}
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/*
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* CGA text video buffer emulation (segment 0xB800).
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*
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* Layout: 80x25 = 4000 bytes, alternating character and attribute bytes.
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* offset = (row * 80 + col) * 2 → character
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* offset = (row * 80 + col) * 2 + 1 → attribute (fg | bg<<4)
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*/
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static uint8_t cga_text_peek(uint16_t offset)
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{
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if (!tui.active || !tui.screen) return 0;
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int cell = offset / 2;
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int cols = tui.cols;
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int row = cell / cols;
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int col = cell % cols;
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if (row >= tui.rows) return 0;
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if (offset & 1)
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return TUI_CELL(row, col).attr;
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else
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return TUI_CELL(row, col).ch;
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}
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static void cga_text_poke(uint16_t offset, uint8_t value)
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{
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if (!tui.active || !tui.screen) return;
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int cell = offset / 2;
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int cols = tui.cols;
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int row = cell / cols;
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int col = cell % cols;
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if (row >= tui.rows) return;
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if (offset & 1)
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TUI_CELL(row, col).attr = value;
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else
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TUI_CELL(row, col).ch = value;
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}
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uint8_t virmem_peek(uint16_t segment, uint16_t offset)
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{
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if (segment == 0x0040)
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return bios_peek(offset);
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if (segment == 0xB800) {
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if (gfx_active())
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return gfx_cga_peek(offset);
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return cga_text_peek(offset);
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}
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/* Unhandled regions return 0 */
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return 0;
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}
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void virmem_poke(uint16_t segment, uint16_t offset, uint8_t value)
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{
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if (segment == 0x0040) {
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bios_poke(offset, value);
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return;
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}
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if (segment == 0xB800) {
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if (gfx_active())
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gfx_cga_poke(offset, value);
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else
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cga_text_poke(offset, value);
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return;
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}
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/* Unhandled regions: silently discard */
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}
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