If you have never dealt with assembly language before, this is going to be hopelessly fast. Sorry about that.
The ESP32 has 16 registers (actually more once you get involved with the
register window business, but never mind that for now.
They are designated a0 through a15.
Two of them are special. a0 is used for subroutine return addresses. a1 is the stack pointer. You can use these as general registers as long as you understand what you are doing.
Instructions are either 16 or 24 bits in size, but you rarely care about that. This is a RISC machine with a load/store architecture. Data flow in the assembler syntax used is right to left, with some exceptions (notably the s32i instruction). Think of it like an assignment statement in C. Here are some examples with C pseudo code in comments
movi a0, 0 ; a0 = 0 and a3, a3, a2 ; a3 = a3 & a2 sub a13, a13, a14 ; a13 -= a14 l32i.n a3, a2, 0 ; a3 = *a2 s32i.n a3, a2, 0 ; *a2 = a3 addi a8, a4, -1 ; a8 = a4 - 1The l32r instruction fetches a 32 bit constant that is stored (dumped) someplace nearby (hence the actual address where the constant is dumped is of little real interest).
l32r a3, [0x0000abab] ; a3 = 0x0000abab
Tom's Computer Info / email@example.com