From cff9b33ea6ece591472ff16fff472fa6def9eb2b Mon Sep 17 00:00:00 2001
From: Jari Vetoniemi <mailroxas@gmail.com>
Date: Tue, 23 Oct 2018 22:41:14 +0300
Subject: memview: u for basic undo

---
 src/memview.c | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/src/memview.c b/src/memview.c
index 07c50b1..422789b 100644
--- a/src/memview.c
+++ b/src/memview.c
@@ -152,6 +152,13 @@ static struct {
       struct { unsigned int x; unsigned int y; } cur;
    } term;
 
+   // kind of hack, lets make real action history someday
+   // but for now, I want u to work at least for offsets
+   struct {
+      size_t data[32];
+      unsigned char pointer;
+   } undo;
+
    struct {
       char data[255];
       unsigned char pointer;
@@ -202,6 +209,17 @@ hex_for_byte(unsigned char byte)
    return hex[byte];
 }
 
+static void
+store_offset(const size_t offset)
+{
+   if (ctx.undo.pointer > 0 && offset == ctx.undo.data[0])
+      return;
+
+   memmove(ctx.undo.data + 1, ctx.undo.data, ctx.undo.pointer * sizeof(ctx.undo.data[0]));
+   ctx.undo.data[0] = ctx.last_hexview.offset;
+   ctx.undo.pointer += (ctx.undo.pointer < ARRAY_SIZE(ctx.undo.data));
+}
+
 static bool
 offset_is_in_named_region(const size_t offset, const struct named_region *named)
 {
@@ -739,6 +757,8 @@ goto_offset(void *arg)
       return;
    }
 
+   store_offset(ctx.hexview.offset);
+
    if (v[0] == '+') {
       ctx.hexview.offset += ret;
    } else if (v[0] == '-') {
@@ -752,6 +772,7 @@ static void
 follow(void *arg)
 {
    (void)arg;
+   store_offset(ctx.hexview.offset);
    const union selection v = get_selection();
    switch (ctx.native_bits) {
       case 64: ctx.hexview.offset = v.u64; break;
@@ -761,6 +782,17 @@ follow(void *arg)
    }
 }
 
+static void
+undo(void *arg)
+{
+   (void)arg;
+   if (!ctx.undo.pointer)
+      return;
+
+   ctx.hexview.offset = ctx.undo.data[0];
+   memmove(ctx.undo.data, ctx.undo.data + 1, --ctx.undo.pointer * sizeof(ctx.undo.data[0]));
+}
+
 static void
 write_bytes(void *arg)
 {
@@ -923,6 +955,7 @@ main(int argc, char *argv[])
       { .seq = { 'q', 0 }, .fun = q_quit },
       { .seq = { 'o', 0 }, .fun = goto_offset },
       { .seq = { 'f', 0 }, .fun = follow },
+      { .seq = { 'u', 0 }, .fun = undo },
       { .seq = { 'w', 0 }, .fun = write_bytes },
    };
 
-- 
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