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-rw-r--r--keyboards/planck/keymaps/callum/keymap.c260
-rw-r--r--keyboards/planck/keymaps/callum/readme.md30
-rw-r--r--keyboards/planck/keymaps/callum/rules.mk7
-rw-r--r--layouts/community/ortho_4x12/callum/config.h14
-rw-r--r--layouts/community/ortho_4x12/callum/keymap.c1
-rw-r--r--users/callum/callum.c130
-rw-r--r--users/callum/oneshot.c57
-rw-r--r--users/callum/oneshot.h31
-rw-r--r--users/callum/readme.md99
-rw-r--r--users/callum/rules.mk3
-rw-r--r--users/callum/swapper.c27
-rw-r--r--users/callum/swapper.h20
12 files changed, 382 insertions, 297 deletions
diff --git a/keyboards/planck/keymaps/callum/keymap.c b/keyboards/planck/keymaps/callum/keymap.c
deleted file mode 100644
index 50c0122a90..0000000000
--- a/keyboards/planck/keymaps/callum/keymap.c
+++ /dev/null
@@ -1,260 +0,0 @@
-#include "planck.h"
-#include "action_layer.h"
-
-#define a KC_A
-#define b KC_B
-#define c KC_C
-#define d KC_D
-#define e KC_E
-#define f KC_F
-#define g KC_G
-#define h KC_H
-#define i KC_I
-#define j KC_J
-#define k KC_K
-#define l KC_L
-#define m KC_M
-#define n KC_N
-#define o KC_O
-#define p KC_P
-#define q KC_Q
-#define r KC_R
-#define s KC_S
-#define t KC_T
-#define u KC_U
-#define v KC_V
-#define w KC_W
-#define x KC_X
-#define y KC_Y
-#define z KC_Z
-
-#define lalt KC_LALT
-#define lctl KC_LCTL
-#define lsft KC_LSFT
-#define ralt KC_RALT
-#define rctl KC_RCTL
-#define rsft KC_RSFT
-
-#define n0 KC_0
-#define n1 KC_1
-#define n2 KC_2
-#define n3 KC_3
-#define n4 KC_4
-#define n5 KC_5
-#define n6 KC_6
-#define n7 KC_7
-#define n8 KC_8
-#define n9 KC_9
-
-#define ampr KC_AMPR
-#define astr KC_ASTR
-#define at KC_AT
-#define bsls KC_BSLS
-#define bspc KC_BSPC
-#define caps KC_CAPS
-#define circ KC_CIRC
-#define comm KC_COMM
-#define dash A(KC_MINS) // en-dash (–); or with shift: em-dash (—)
-#define del KC_DEL
-#define dlr KC_DLR
-#define dot KC_DOT
-#define ent KC_ENT
-#define eql KC_EQL
-#define esc KC_ESC
-#define exlm KC_EXLM
-#define grv KC_GRV
-#define hash KC_HASH
-#define lbrc KC_LBRC
-#define lcbr KC_LCBR
-#define lprn KC_LPRN
-#define mins KC_MINS
-#define perc KC_PERC
-#define pipe KC_PIPE
-#define plus KC_PLUS
-#define quot KC_QUOT
-#define rbrc KC_RBRC
-#define rcbr KC_RCBR
-#define rprn KC_RPRN
-#define scln KC_SCLN
-#define slsh KC_SLSH
-#define spc KC_SPC
-#define tab KC_TAB
-#define tild KC_TILD
-
-#define down KC_DOWN
-#define home G(KC_LEFT)
-#define end G(KC_RGHT)
-#define up KC_UP
-#define pgdn KC_PGDN
-#define pgup KC_PGUP
-#define left KC_LEFT
-#define rght KC_RGHT
-
-#define tabl G(S(KC_LBRC))
-#define tabr G(S(KC_RBRC))
-#define fwd G(KC_RBRC)
-#define back G(KC_LBRC)
-#define slup S(A(KC_UP)) // Previous unread in Slack
-#define sldn S(A(KC_DOWN)) // Next unread in Slack
-
-#define ctl1 C(KC_1) // Desktop 1 (6 with shift)
-#define ctl2 C(KC_2) // Desktop 2 (7 with shift)
-#define ctl3 C(KC_3) // Desktop 3 (8 with shift)
-#define ctl4 C(KC_4) // Desktop 4 (9 with shift)
-#define ctl5 C(KC_5) // Desktop 5 (10 with shift)
-#define ctl6 C(KC_6) // Screenshot
-#define ctl7 C(KC_7) // Brightness up
-#define ctl8 C(KC_8) // Brightness down
-
-#define f1 KC_F1
-#define f2 KC_F2
-#define f3 KC_F3
-#define f4 KC_F4
-#define f5 KC_F5
-#define f6 KC_F6
-#define f7 KC_F7
-#define f8 KC_F8
-#define f9 KC_F9
-#define f10 KC_F10
-#define f11 KC_F11
-#define f12 KC_F12
-#define f13 KC_F13
-#define f14 KC_F14
-#define f15 KC_F15
-#define f16 KC_F16
-#define f17 KC_F17
-#define f18 KC_F18
-#define f19 KC_F19
-#define f20 KC_F20
-
-#define mute KC_MUTE
-#define next KC_MNXT
-#define play KC_MPLY
-#define prev KC_MPRV
-#define vold KC_VOLD
-#define volu KC_VOLU
-
-#define symb MO(SYMB)
-#define move MO(MOVE)
-#define func MO(FUNC)
-
-#define rset RESET
-#define powr KC_POWER
-
-#define ____ KC_TRNS
-#define xxxx KC_NO
-
-extern keymap_config_t keymap_config;
-
-enum planck_layers {
- BASE,
- SYMB,
- MOVE,
- FUNC,
-};
-
-enum planck_keycodes {
- // Curly quotes
- lcqt = SAFE_RANGE,
- rcqt,
-
- // "Smart" mods
- cmd,
-};
-
-const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
- [BASE] = LAYOUT_planck_grid(
- tab, q, w, f, p, g, j, l, u, y, scln, mins,
- bspc, a, r, s, t, d, h, n, e, i, o, quot,
- lsft, z, x, c, v, b, k, m, comm, dot, slsh, rsft,
- func, lctl, lalt, cmd, move, ent, spc, symb, cmd, ralt, rctl, func
- ),
-
- [SYMB] = LAYOUT_planck_grid(
- esc, n7, n5, n3, n1, n9, n8, n0, n2, n4, n6, dash,
- lcqt, at, dlr, eql, lprn, lbrc, rbrc, rprn, astr, hash, plus, rcqt,
- ____, grv, pipe, bsls, lcbr, tild, circ, rcbr, ampr, exlm, perc, ____,
- ____, ____, ____, ____, ____, ____, ____, ____, ____, ____, ____, ____
- ),
-
- [MOVE] = LAYOUT_planck_grid(
- esc, ctl1, ctl2, ctl3, ctl4, ctl5, ctl6, home, up, end, xxxx, xxxx,
- del, play, volu, tabl, tabr, slup, ctl7, left, down, rght, caps, xxxx,
- ____, mute, vold, back, fwd, sldn, ctl8, pgdn, pgup, xxxx, xxxx, ____,
- ____, ____, ____, ____, ____, ____, ____, ____, ____, ____, ____, ____
- ),
-
- [FUNC] = LAYOUT_planck_grid(
- rset, f7, f5, f3, f1, f9, f8, f10, f2, f4, f6, xxxx,
- xxxx, f17, f15, f13, f11, f19, f18, f20, f12, f14, f16, xxxx,
- ____, xxxx, xxxx, xxxx, xxxx, xxxx, xxxx, xxxx, xxxx, xxxx, xxxx, ____,
- ____, ____, ____, ____, ____, ____, ____, ____, ____, ____, ____, ____
- ),
-};
-
-bool send_string_if_keydown(
- keyrecord_t *record,
- const char *unshifted,
- const char *shifted) {
- if (record->event.pressed) {
- if (shifted) {
- uint8_t shifts = get_mods() & MOD_MASK_SHIFT;
- if (shifts) {
- del_mods(shifts);
- send_string(shifted);
- add_mods(shifts);
- } else {
- send_string(unshifted);
- }
- } else {
- send_string(unshifted);
- }
- }
- return true;
-}
-
-// Holding both cmd keys will instead register as cmd + ctl
-bool smart_cmd(keyrecord_t *record) {
- static int cmd_keys_down = 0;
-
- if (record->event.pressed) {
- if (cmd_keys_down == 0) {
- register_code(KC_LCMD);
- } else {
- register_code(KC_LCTL);
- }
- cmd_keys_down++;
- } else {
- if (cmd_keys_down == 1) {
- unregister_code(KC_LCMD);
- } else {
- unregister_code(KC_LCTL);
- }
- cmd_keys_down--;
- }
- return true;
-}
-
-bool process_record_user(uint16_t keycode, keyrecord_t *record) {
- switch (keycode) {
- // The macOS shortcuts for curly quotes are horrible, so this rebinds
- // them so that shift toggles single–double instead of left–right, and
- // then both varieties of left quote can share one key, and both
- // varieties of right quote share another.
- case lcqt:
- return send_string_if_keydown(
- record,
- SS_LALT("]"), // left single quote (‘)
- SS_LALT("[")); // left double quote (“)
- case rcqt:
- return send_string_if_keydown(
- record,
- SS_LALT(SS_LSFT("]")), // right single quote (’)
- SS_LALT(SS_LSFT("["))); // right double quote (”)
-
- // cmd + cmd -> cmd + ctl
- case cmd:
- return smart_cmd(record);
- }
- return true;
-}
diff --git a/keyboards/planck/keymaps/callum/readme.md b/keyboards/planck/keymaps/callum/readme.md
deleted file mode 100644
index 471de2b741..0000000000
--- a/keyboards/planck/keymaps/callum/readme.md
+++ /dev/null
@@ -1,30 +0,0 @@
-# callum’s planck layout
-
-This is a layout for the grid planck, built with a few ideals in mind:
-
-- Consistent and minimal response times should be maintained. Keys that react
- differently depending on whether they are tapped or held, keys that react
- differently if they are double tapped, etc. should be avoided – they
- inevitably send their keycode later than a normal key – interrupting the
- immediate feedback from the screen. Therefore we restrict ourselves to
- chording as our only means of getting more than one symbol out of a single
- physical key.
-
-- The hands should never need to leave the home position. The usual culprit for
- this is the arrow cluster, so the arrow cluster should be as close to home as
- possible.
-
-- There should be two of every modifier (one on each side), otherwise certain
- long key combinations become hard to make.
-
-- It should be possible to do things you might want to do while using the mouse
- with only the left hand (e.g. change tabs, navigate back or forwards in
- browser history).
-
-- Symbols should be arranged so that the most frequently used are easiest to
- reach. This includes numbers, and lower numbers are more commonly used than
- higher ones. (number arrangement borrowed from [dustypomeleau’s minidox
- layout][]).
-
-[dustypomeleau’s minidox layout]: https://github.com/qmk/qmk_firmware/tree/master/keyboards/minidox/keymaps/dustypomerleau
-[keymap.c]: keymap.c
diff --git a/keyboards/planck/keymaps/callum/rules.mk b/keyboards/planck/keymaps/callum/rules.mk
deleted file mode 100644
index 9615222d1b..0000000000
--- a/keyboards/planck/keymaps/callum/rules.mk
+++ /dev/null
@@ -1,7 +0,0 @@
-BOOTMAGIC_ENABLE = no
-MOUSEKEY_ENABLE = no
-CONSOLE_ENABLE = no
-COMMAND_ENABLE = yes
-MIDI_ENABLE = no
-AUDIO_ENABLE = yes
-RGBLIGHT_ENABLE = no
diff --git a/layouts/community/ortho_4x12/callum/config.h b/layouts/community/ortho_4x12/callum/config.h
new file mode 100644
index 0000000000..8034fe51b6
--- /dev/null
+++ b/layouts/community/ortho_4x12/callum/config.h
@@ -0,0 +1,14 @@
+#pragma once
+
+#define LAYOUT_callum( \
+ KEY00, KEY01, KEY02, KEY03, KEY04, KEY05, KEY06, KEY07, KEY08, KEY09, \
+ KEY10, KEY11, KEY12, KEY13, KEY14, KEY15, KEY16, KEY17, KEY18, KEY19, \
+ KEY20, KEY21, KEY22, KEY23, KEY24, KEY25, KEY26, KEY27, KEY28, KEY29, \
+ KEY30, KEY31, KEY32, KEY33 \
+) \
+LAYOUT_ortho_4x12( \
+ KEY00, KEY01, KEY02, KEY03, KEY04, KC_NO, KC_NO, KEY05, KEY06, KEY07, KEY08, KEY09, \
+ KEY10, KEY11, KEY12, KEY13, KEY14, KC_NO, KC_NO, KEY15, KEY16, KEY17, KEY18, KEY19, \
+ KEY20, KEY21, KEY22, KEY23, KEY24, KC_NO, KC_NO, KEY25, KEY26, KEY27, KEY28, KEY29, \
+ KC_NO, KC_NO, KC_NO, KEY30, KEY31, KC_NO, KC_NO, KEY32, KEY33, KC_NO, KC_NO, KC_NO \
+)
diff --git a/layouts/community/ortho_4x12/callum/keymap.c b/layouts/community/ortho_4x12/callum/keymap.c
new file mode 100644
index 0000000000..acff75905d
--- /dev/null
+++ b/layouts/community/ortho_4x12/callum/keymap.c
@@ -0,0 +1 @@
+// Intentionally empty. See /users/callum/readme.md.
diff --git a/users/callum/callum.c b/users/callum/callum.c
new file mode 100644
index 0000000000..4661902af5
--- /dev/null
+++ b/users/callum/callum.c
@@ -0,0 +1,130 @@
+#include QMK_KEYBOARD_H
+
+#include "oneshot.h"
+#include "swapper.h"
+
+#define HOME G(KC_LEFT)
+#define END G(KC_RGHT)
+#define FWD G(KC_RBRC)
+#define BACK G(KC_LBRC)
+#define TABL G(S(KC_LBRC))
+#define TABR G(S(KC_RBRC))
+#define SPCL A(G(KC_LEFT))
+#define SPCR A(G(KC_RGHT))
+#define LA_SYM MO(SYM)
+#define LA_NAV MO(NAV)
+
+enum layers {
+ DEF,
+ SYM,
+ NAV,
+ NUM,
+};
+
+enum keycodes {
+ // Custom oneshot mod implementation with no timers.
+ OS_SHFT = SAFE_RANGE,
+ OS_CTRL,
+ OS_ALT,
+ OS_CMD,
+
+ SW_WIN, // Switch to next window (cmd-tab)
+ SW_LANG, // Switch to next input language (ctl-spc)
+};
+
+const uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {
+ [DEF] = LAYOUT_callum(
+ KC_Q, KC_W, KC_F, KC_P, KC_G, KC_J, KC_L, KC_U, KC_Y, KC_QUOT,
+ KC_A, KC_R, KC_S, KC_T, KC_D, KC_H, KC_N, KC_E, KC_I, KC_O,
+ KC_Z, KC_X, KC_C, KC_V, KC_B, KC_K, KC_M, KC_COMM, KC_DOT, KC_SLSH,
+ LA_NAV, KC_LSFT, KC_SPC, LA_SYM
+ ),
+
+ [SYM] = LAYOUT_callum(
+ KC_ESC, KC_LBRC, KC_LCBR, KC_LPRN, KC_TILD, KC_CIRC, KC_RPRN, KC_RCBR, KC_RBRC, KC_GRV,
+ KC_MINS, KC_ASTR, KC_EQL, KC_UNDS, KC_DLR, KC_HASH, OS_CMD, OS_ALT, OS_CTRL, OS_SHFT,
+ KC_PLUS, KC_PIPE, KC_AT, KC_BSLS, KC_PERC, XXXXXXX, KC_AMPR, KC_SCLN, KC_COLN, KC_EXLM,
+ _______, _______, _______, _______
+ ),
+
+ [NAV] = LAYOUT_callum(
+ KC_TAB, SW_WIN, TABL, TABR, KC_VOLU, RESET, HOME, KC_UP, END, KC_DEL,
+ OS_SHFT, OS_CTRL, OS_ALT, OS_CMD, KC_VOLD, KC_CAPS, KC_LEFT, KC_DOWN, KC_RGHT, KC_BSPC,
+ SPCL, SPCR, BACK, FWD, KC_MPLY, XXXXXXX, KC_PGDN, KC_PGUP, SW_LANG, KC_ENT,
+ _______, _______, _______, _______
+ ),
+
+ [NUM] = LAYOUT_callum(
+ KC_7, KC_5, KC_3, KC_1, KC_9, KC_8, KC_0, KC_2, KC_4, KC_6,
+ OS_SHFT, OS_CTRL, OS_ALT, OS_CMD, KC_F11, KC_F10, OS_CMD, OS_ALT, OS_CTRL, OS_SHFT,
+ KC_F7, KC_F5, KC_F3, KC_F1, KC_F9, KC_F8, KC_F12, KC_F2, KC_F4, KC_F6,
+ _______, _______, _______, _______
+ ),
+};
+
+bool is_oneshot_cancel_key(uint16_t keycode) {
+ switch (keycode) {
+ case LA_SYM:
+ case LA_NAV:
+ return true;
+ default:
+ return false;
+ }
+}
+
+bool is_oneshot_ignored_key(uint16_t keycode) {
+ switch (keycode) {
+ case LA_SYM:
+ case LA_NAV:
+ case KC_LSFT:
+ case OS_SHFT:
+ case OS_CTRL:
+ case OS_ALT:
+ case OS_CMD:
+ return true;
+ default:
+ return false;
+ }
+}
+
+bool sw_win_active = false;
+bool sw_lang_active = false;
+
+oneshot_state os_shft_state = os_up_unqueued;
+oneshot_state os_ctrl_state = os_up_unqueued;
+oneshot_state os_alt_state = os_up_unqueued;
+oneshot_state os_cmd_state = os_up_unqueued;
+
+bool process_record_user(uint16_t keycode, keyrecord_t *record) {
+ update_swapper(
+ &sw_win_active, KC_LGUI, KC_TAB, SW_WIN,
+ keycode, record
+ );
+ update_swapper(
+ &sw_lang_active, KC_LCTL, KC_SPC, SW_LANG,
+ keycode, record
+ );
+
+ update_oneshot(
+ &os_shft_state, KC_LSFT, OS_SHFT,
+ keycode, record
+ );
+ update_oneshot(
+ &os_ctrl_state, KC_LCTL, OS_CTRL,
+ keycode, record
+ );
+ update_oneshot(
+ &os_alt_state, KC_LALT, OS_ALT,
+ keycode, record
+ );
+ update_oneshot(
+ &os_cmd_state, KC_LCMD, OS_CMD,
+ keycode, record
+ );
+
+ return true;
+}
+
+layer_state_t layer_state_set_user(layer_state_t state) {
+ return update_tri_layer_state(state, SYM, NAV, NUM);
+}
diff --git a/users/callum/oneshot.c b/users/callum/oneshot.c
new file mode 100644
index 0000000000..33ec3895e2
--- /dev/null
+++ b/users/callum/oneshot.c
@@ -0,0 +1,57 @@
+#include "oneshot.h"
+
+void update_oneshot(
+ oneshot_state *state,
+ uint16_t mod,
+ uint16_t trigger,
+ uint16_t keycode,
+ keyrecord_t *record
+) {
+ if (keycode == trigger) {
+ if (record->event.pressed) {
+ // Trigger keydown
+ if (*state == os_up_unqueued) {
+ register_code(mod);
+ }
+ *state = os_down_unused;
+ } else {
+ // Trigger keyup
+ switch (*state) {
+ case os_down_unused:
+ // If we didn't use the mod while trigger was held, queue it.
+ *state = os_up_queued;
+ break;
+ case os_down_used:
+ // If we did use the mod while trigger was held, unregister it.
+ *state = os_up_unqueued;
+ unregister_code(mod);
+ break;
+ default:
+ break;
+ }
+ }
+ } else {
+ if (record->event.pressed) {
+ if (is_oneshot_cancel_key(keycode) && *state != os_up_unqueued) {
+ // Cancel oneshot on designated cancel keydown.
+ *state = os_up_unqueued;
+ unregister_code(mod);
+ }
+ } else {
+ if (!is_oneshot_ignored_key(keycode)) {
+ // On non-ignored keyup, consider the oneshot used.
+ switch (*state) {
+ case os_down_unused:
+ *state = os_down_used;
+ break;
+ case os_up_queued:
+ *state = os_up_unqueued;
+ unregister_code(mod);
+ break;
+ default:
+ break;
+ }
+ }
+ }
+ }
+}
diff --git a/users/callum/oneshot.h b/users/callum/oneshot.h
new file mode 100644
index 0000000000..a6b8e17742
--- /dev/null
+++ b/users/callum/oneshot.h
@@ -0,0 +1,31 @@
+#pragma once
+
+#include QMK_KEYBOARD_H
+
+// Represents the four states a oneshot key can be in
+typedef enum {
+ os_up_unqueued,
+ os_up_queued,
+ os_down_unused,
+ os_down_used,
+} oneshot_state;
+
+// Custom oneshot mod implementation that doesn't rely on timers. If a mod is
+// used while it is held it will be unregistered on keyup as normal, otherwise
+// it will be queued and only released after the next non-mod keyup.
+void update_oneshot(
+ oneshot_state *state,
+ uint16_t mod,
+ uint16_t trigger,
+ uint16_t keycode,
+ keyrecord_t *record
+);
+
+// To be implemented by the consumer. Defines keys to cancel oneshot mods.
+bool is_oneshot_cancel_key(uint16_t keycode);
+
+// To be implemented by the consumer. Defines keys to ignore when determining
+// whether a oneshot mod has been used. Setting this to modifiers and layer
+// change keys allows stacking multiple oneshot modifiers, and carrying them
+// between layers.
+bool is_oneshot_ignored_key(uint16_t keycode);
diff --git a/users/callum/readme.md b/users/callum/readme.md
new file mode 100644
index 0000000000..24b71038b6
--- /dev/null
+++ b/users/callum/readme.md
@@ -0,0 +1,99 @@
+A keymap for 34 keys with 4 layers and no mod-tap.
+
+![](https://raw.githubusercontent.com/callum-oakley/keymap/master/keymap.svg)
+
+## Details
+
+- Hold `sym` to activate the symbols layer.
+- Hold `nav` to activate the navigation layer.
+- Hold `sym` and `nav` together to activate the numbers layer.
+- The home row modifiers are oneshot so that it's possible to modify the
+ keys on the base layer, where there are no dedicated modifiers.
+- `swap win` sends `cmd-tab` for changing focus in macOS but holds `cmd`
+ between consecutive presses.
+- `swap lang` behaves similarly but sends `ctrl-space`, for changing input
+ language in macOS.
+
+## Oneshot modifiers
+
+The home row modifiers can either be held and used as normal, or if no other
+keys are pressed while a modifier is down, the modifier will be queued and
+applied to the next non-modifier keypress. For example to type `shift-cmd-t`,
+type `sym-o-n` (or `nav-a-t`), release, then hit `t`.
+
+You can and should hit chords as fast as you like because there are no timers
+involved.
+
+Cancel unused modifiers by tapping `nav` or `sym`.
+
+### Userspace oneshot implementation
+
+For my usage patterns I was hitting stuck modifiers frequently with [`OSM`][]
+(maybe related to [#3963][]?). I'd like to try to help fix this in QMK proper,
+but implementing oneshot mods in userspace first was:
+
+1. Fun.
+2. A good exploration of how I think oneshot mods should work without timers.
+
+So in the meantime, this [userspace oneshot implementation][] is working well
+for me.
+
+## Swapper
+
+`swap win` sends `cmd-tab`, but holds `cmd` between consecutive keypresses.
+`cmd` is released when some other key is hit or released. For example
+
+ nav down, swap win, swap win, nav up -> cmd down, tab, tab, cmd up
+ nav down, swap win, enter -> cmd down, tab, cmd up, enter
+
+`swap lang` sends `ctrl-space` to swap input languages in macOS and behaves
+similarly.
+
+[Swapper implementation.][]
+
+## Why no mod-tap?
+
+[Mod-tap][] seems to be by far the most popular tool among users of tiny
+keyboards to answer the question of where to put the modifiers, and in the
+right hands it can clearly work brilliantly, but I've always found myself error
+prone and inconsistent with it.
+
+With dedicated modifiers, there are three ways one might type `ctrl-c`:
+
+ ctrl down, ctrl up, c down, c up
+ ctrl down, c down, ctrl up, c up
+ ctrl down, c down, c up, ctrl up
+
+Basically, you never have to worry about the keyups, as long as the keydowns
+occur in the correct order. Similarly, there are three ways one might type
+`ac`:
+
+ a down, a up, c down, c up
+ a down, c down, a up, c up
+ a down, c down, c up, a up
+
+Replace `a` with `ctrl` and this is exactly what we had before! So if we want
+to put `a` and `ctrl` on the same key we have a problem, because without
+considering timing these sequences become ambiguous. So let's consider timing.
+
+The solution to the ambiguity that QMK employs is to configure the
+`TAPPING_TERM` and consider a key held rather than tapped if it is held for
+long enough. My problem with this is that it forces you to slow down to use
+modifiers. By its very nature the tapping term must be longer than the longest
+you would ever hold a key while typing on the slowest laziest Sunday afternoon.
+I'm not typing at 100% speed at all times, but when I am, having to think about
+timing and consciously slow down for certain actions never fails to trip me up.
+
+So alas, mod-tap is not for me -- but if it works for you, more power to you.
+:)
+
+* * *
+
+[My github][]
+
+[`OSM`]: /docs/one_shot_keys.md
+[#3963]: https://github.com/qmk/qmk_firmware/issues/3963
+[userspace oneshot implementation]: oneshot.c
+[swapper implementation.]: swapper.c
+[Mod-tap]: https://github.com/qmk/qmk_firmware/blob/master/docs/mod_tap.md
+[My github]: https://github.com/callum-oakley
diff --git a/users/callum/rules.mk b/users/callum/rules.mk
new file mode 100644
index 0000000000..2d98e02c55
--- /dev/null
+++ b/users/callum/rules.mk
@@ -0,0 +1,3 @@
+SRC += callum.c
+SRC += oneshot.c
+SRC += swapper.c
diff --git a/users/callum/swapper.c b/users/callum/swapper.c
new file mode 100644
index 0000000000..736b2fef0c
--- /dev/null
+++ b/users/callum/swapper.c
@@ -0,0 +1,27 @@
+#include "swapper.h"
+
+void update_swapper(
+ bool *active,
+ uint16_t cmdish,
+ uint16_t tabish,
+ uint16_t trigger,
+ uint16_t keycode,
+ keyrecord_t *record
+) {
+ if (keycode == trigger) {
+ if (record->event.pressed) {
+ if (!*active) {
+ *active = true;
+ register_code(cmdish);
+ }
+ register_code(tabish);
+ } else {
+ unregister_code(tabish);
+ // Don't unregister cmdish until some other key is hit or released.
+ }
+ } else if (*active) {
+ unregister_code(cmdish);
+ *active = false;
+ }
+}
+
diff --git a/users/callum/swapper.h b/users/callum/swapper.h
new file mode 100644
index 0000000000..ad47fd96ce
--- /dev/null
+++ b/users/callum/swapper.h
@@ -0,0 +1,20 @@
+#pragma once
+
+#include QMK_KEYBOARD_H
+
+// Implements cmd-tab like behaviour on a single key. On first tap of trigger
+// cmdish is held and tabish is tapped -- cmdish then remains held until some
+// other key is hit or released. For example:
+//
+// trigger, trigger, a -> cmd down, tab, tab, cmd up, a
+// nav down, trigger, nav up -> nav down, cmd down, tab, cmd up, nav up
+//
+// This behaviour is useful for more than just cmd-tab, hence: cmdish, tabish.
+void update_swapper(
+ bool *active,
+ uint16_t cmdish,
+ uint16_t tabish,
+ uint16_t trigger,
+ uint16_t keycode,
+ keyrecord_t *record
+);