grid: track both linear and row,col cursor

csi.c

@@ -96,7 +96,7 @@ csi_dispatch(struct terminal *term, uint8_t final)
 
         case 'J': {
             assert(term->vt.params.idx == 0);
-            int start = term->grid.cursor / term->grid.cols * term->grid.cols;
+            int start = grid_cursor_linear(&term->grid, term->grid.cursor.row, 0);
             int end = term->grid.cols * term->grid.rows;
             grid_erase(&term->grid, start, end);
             return true;
@@ -104,10 +104,10 @@ csi_dispatch(struct terminal *term, uint8_t final)
 
         case 'K': {
             assert(term->vt.params.idx == 0);
-            int start = term->grid.cursor;
-            int end = (start + term->grid.cols - 1) / term->grid.cols * term->grid.cols - 1;
-            assert(start <= end);
-            assert((end + 1) % term->grid.cols == 0);
+            int start = term->grid.linear_cursor;
+            int end = grid_cursor_linear(
+                &term->grid, term->grid.cursor.row, term->grid.cols - 1);
+            LOG_DBG("K: %d -> %d", start, end);
 
             grid_erase(&term->grid, start, end);
             return true;
@@ -115,13 +115,13 @@ csi_dispatch(struct terminal *term, uint8_t final)
 
         case 'C': {
             int count = term->vt.params.idx > 0 ? term->vt.params.v[0].value : 1;
-            grid_cursor_move(&term->grid, count);
+            grid_cursor_right(&term->grid, count);
             return true;
         }
 
         case 'D': {
             int count = term->vt.params.idx > 0 ? term->vt.params.v[0].value : 1;
-            grid_cursor_move(&term->grid, -count);
+            grid_cursor_left(&term->grid, count);
             return true;
         }
 

grid.c

@@ -1,6 +1,10 @@
 #include "grid.h"
 
 #include <string.h>
+#include <assert.h>
+
+#define min(x, y) ((x) < (y) ? (x) : (y))
+#define max(x, y) ((x) > (y) ? (x) : (y))
 
 void
 grid_erase(struct grid *grid, int start, int end)
@@ -17,19 +21,74 @@ grid_erase(struct grid *grid, int start, int end)
     }
 }
 
-void
-grid_cursor_move(struct grid *grid, int cols)
+int
+grid_cursor_linear(const struct grid *grid, int row, int col)
 {
-    int new_cursor = grid->cursor + cols;
-    grid->cells[grid->cursor].dirty = true;
-    grid->cells[new_cursor].dirty = true;
-    grid->cursor = new_cursor;
+    return row * grid->cols + col;
+}
+
+void
+grid_cursor_to(struct grid *grid, int row, int col)
+{
+    assert(row >= 0);
+    assert(row < grid->rows);
+    assert(col >= 0);
+    assert(col < grid->cols);
+
+    int new_linear = row * grid->cols + col;
+    assert(new_linear >= 0);
+    assert(new_linear < grid->rows * grid->cols);
+
+    grid->cells[grid->linear_cursor].dirty = true;
+    grid->cells[new_linear].dirty = true;
+    grid->dirty = true;
+    grid->print_needs_wrap = false;
+
+    grid->linear_cursor = new_linear;
+    grid->cursor.col = col;
+    grid->cursor.row = row;
+}
+
+void
+grid_cursor_left(struct grid *grid, int count)
+{
+    int move_amount = min(grid->cursor.col, count);
+    int new_linear = grid->linear_cursor - move_amount;
+    int new_col = grid->cursor.col - move_amount;
+
+    assert(new_linear >= 0);
+    assert(new_linear < grid->rows * grid->cols);
+    assert(new_col >= 0);
+    assert(new_col < grid->cols);
+
+    grid->cells[grid->linear_cursor].dirty = true;
+    grid->cells[new_linear].dirty = true;
+
+    grid->linear_cursor = new_linear;
+    grid->cursor.col = new_col;
+
     grid->dirty = true;
     grid->print_needs_wrap = false;
 }
 
 void
-grid_cursor_to(struct grid *grid, int pos)
+grid_cursor_right(struct grid *grid, int count)
 {
-    grid_cursor_move(grid, pos - grid->cursor);
+    int move_amount = min(grid->cols - grid->cursor.col - 1, count);
+    int new_linear = grid->linear_cursor + move_amount;
+    int new_col = grid->cursor.col + move_amount;
+
+    assert(new_linear >= 0);
+    assert(new_linear < grid->rows * grid->cols);
+    assert(new_col >= 0);
+    assert(new_col < grid->cols);
+
+    grid->cells[grid->linear_cursor].dirty = true;
+    grid->cells[new_linear].dirty = true;
+
+    grid->linear_cursor = new_linear;
+    grid->cursor.col = new_col;
+
+    grid->dirty = true;
+    grid->print_needs_wrap = false;
 }

grid.h

@@ -4,5 +4,11 @@
 
 void grid_erase(struct grid *grid, int start, int end);
 
-void grid_cursor_to(struct grid *grid, int pos);
-void grid_cursor_move(struct grid *grid, int cols);
+void grid_cursor_to(struct grid *grid, int row, int col);
+void grid_cursor_left(struct grid *grid, int count);
+void grid_cursor_right(struct grid *grid, int count);
+
+int grid_cursor_linear(const struct grid *grid, int row, int col);
+
+//void grid_cursor_to(struct grid *grid, int pos);
+//void grid_cursor_move(struct grid *grid, int cols);

main.c

@@ -97,7 +97,7 @@ grid_render(struct context *c)
 
             cell->dirty = false;
 
-            bool has_cursor = c->term.grid.cursor == cell_idx;
+            bool has_cursor = c->term.grid.linear_cursor == cell_idx;
 
             int y_ofs = row * c->term.grid.cell_height + c->fextents.ascent;
             int x_ofs = col * c->term.grid.cell_width;

terminal.h

@@ -28,8 +28,13 @@ struct grid {
     int cell_width;
     int cell_height;
 
-    int cursor;
+    int linear_cursor;
+    struct {
+        int row;
+        int col;
+    } cursor;
     bool print_needs_wrap;
+
     struct cell *cells;
 
     uint32_t foreground;

vt.c

@@ -158,13 +158,11 @@ action(struct terminal *term, enum action action, uint8_t c)
         LOG_DBG("execute: 0x%02x", c);
         switch (c) {
         case '\r':
-            grid_cursor_to(
-                &term->grid,
-                term->grid.cursor / term->grid.cols * term->grid.cols);
+            grid_cursor_left(&term->grid, term->grid.cursor.col);
             break;
 
         case '\b':
-            grid_cursor_move(&term->grid, -1);
+            grid_cursor_left(&term->grid, 1);
             break;
         }
 
@@ -179,9 +177,9 @@ action(struct terminal *term, enum action action, uint8_t c)
 
     case ACTION_PRINT: {
         if (term->grid.print_needs_wrap)
-            grid_cursor_move(&term->grid, 1);
+            grid_cursor_to(&term->grid, term->grid.cursor.row + 1, 0);
 
-        struct cell *cell = &term->grid.cells[term->grid.cursor];
+        struct cell *cell = &term->grid.cells[term->grid.linear_cursor];
 
         cell->dirty = true;
 
@@ -197,8 +195,8 @@ action(struct terminal *term, enum action action, uint8_t c)
 
         cell->attrs = term->vt.attrs;
 
-        if ((term->grid.cursor + 1) % term->grid.cols)
-            grid_cursor_move(&term->grid, 1);
+        if (term->grid.cursor.col < term->grid.cols - 1)
+            grid_cursor_right(&term->grid, 1);
         else
             term->grid.print_needs_wrap = true;